rsRecordSet.Source = "SELECT *                      " & _
                         "FROM   tsrtime                " & _
                         "WHERE  date    = #" & dt & "# " & _
                         "  AND  agentid  = " & id

                         " . . . " & _

                         "  AND  agentid = '" & id & "'"

                         "WHERE  date = TODATE('" & dt & "', 'MM-DD-YY')" & _

                         " . . . "

Option Explicit
Private WithEvents cno            As ADODB.Connection
Private WithEvents rs As ADODB.Recordset
Dim i As Long
Dim j As Integer

Private Sub Form_Load()
    ' This would ba a good place to open the connection.
    FillCombo
End Sub

Private Sub FillCombo()

    Dim cn As ADODB.Connection
    Dim rs As ADODB.Recordset
    Dim intLoop As Integer
    Set cn = New ADODB.Connection
    Set rs = New ADODB.Recordset

    ' There’s no need to create a new connection here.  Just use cno, which you
    ' have defined with module-scope.  Test for whether it is open;  if not use
     ' cno.open. Otherwise, just use it.  One connection is all you need.
    cn.ConnectionString = "driver = {sqlserver};" & _
                          "Data Source = SQLDSN;" & _
                          "UserId=reddy;" & _
                          "Password=reddy04"
    cn.Open "sqldsn"

    rs.Open "SELECT date, agentid " & _
            "FROM   tsrtime       ", _
            cn, adOpenForwardOnly

    ' While / Wend is considered outdated.   Use Do Until rs.EOF
    '                                            Loop      instead
    While rs.EOF = False
        Listdt.AddItem (rs.Fields("date").Value)
        List1.AddItem (rs.Fields("agentid").Value)
        rs.MoveNext
    Wend

    ' I recommend single-statement Ifs in cases like this:
     If rs.State = adStateOpen Then rs.Close
    Set rs = Nothing

     If cn.State = adStateOpen Then cn.Close
    Set cn = Nothing

End Sub

Public Sub Cmdret_Click()

    Dim cn As ADODB.Connection
    Dim rs As ADODB.Recordset
    Set cno = New ADODB.Connection
    Set rs  = New ADODB.Recordset
    cno.ConnectionString = "driver = {sqlserver};" & _
                           "Data Source = SQLDSN;" & _
                           "UserId=reddy;" & _
                           "Password=reddy04"
    cno.Open "sqldsn"

    ' What is ‘i’ here?  Where does its value come from?
    ' As far as I can tell, it is never set, so it = 0 . . .
    If Listdt.Selected(i) = True And List1.Selected(i) = True Then
        ' You have an extraneous space in two locations here:
        '     Listdt.List(i) & " ' "
        '                       ¯
        ' and 
        '     List1.List(i) & " '"
        '                      ¯
        rs.Open "SELECT * " & _
                "FROM tsrtime " & _
                "WHERE date='" & Listdt.List(i) & " ' " & _
                "AND agentid = '" & List1.List(i) & " '", _
                cno, adOpenStatic, adLockPessimistic

        ' This is an awkward syntax.  I suggest:
        '            rs!starttime, and so on.
        Text1.Text = rs.Fields("starttime")
        Text2.Text = rs.Fields("endtime")
        Text3.Text = rs.Fields("breaklength")
        Text4.Text = rs.Fields("reasoncode")
        Text5.Text = rs.Fields("paycode")

    Else
        ' Using all caps gives the impression that you are shouting.
        MsgBox "NO RECORDS FOUND FOR THE USER" + List1.List(i) + "On " + Listdt.List(i), _
               vbExclamation, vbOK  ' You have a messagebox constant (vbOK) as the title here . . .
    End If

   'While rs.EOF = False
   'If rs.EOF = True Then
      rs.MoveNext   ' Why are you repositioning the recordset?

    'rs.MoveNext

   'Wend
   'End If
   'Next

    Text1.SetFocus
    List1.Enabled = False
    Listdt.Enabled = False

End Sub

Private Sub cmdExit_Click()
    cno.Close
    'cno = Nothing
    End
End Sub

Private Sub WriteDataFromControls()
    ' You declared a module scope recordset ‘rs,’ which permits this
    ' routine to finction—it knows about a recordset called ‘rs.’
    ' But everyplace except here that you use ‘rs,’ you create a 
    ' procedure-scope Recordset of that name first.  The result
    ' is that though the name is the same, that name refers to 
    ' entirely different objects.  If you prefaced your module-
    ' scope variables with ‘m,’ this wouldn’t happen . . .

    rs.Fields("starttime").Value = Text1.Text
    rs.Fields("endtime").Value = Text2.Text
    rs.Fields("breaklength").Value = Text3.Text
    rs.Fields("reasoncode").Value = Text4.Text
    rs.Fields("paycode").Value = Text5.Text
    rs.Update
End Sub

Private Sub cmdSave_Click()

    'MsgBox " Connection" + cno.ConnectionString
    'Dim strsql2 As String

    'If Listdt.Selected(i) = True And List1.Selected(i) = True Then
    'strsql2 = "INSERT INTO tsrtime " & _
    '          "VALUES ('" & Text1.Text & ",'" & Text2.Text & "','" & Text3.Text & "','" & Text4.Text & "','" & Text5.Text & "')"
     '  cno.Open "sqldsn"
     '  cno.Execute strsql2
     ' End If


    WriteDataFromControls
    MsgBox " 1 row updated "
'rs.Update
End Sub

—————————————————————————————————————————————————————————————

Option Explicit
Private mCno As ADODB.Connection
Private mRs  As ADODB.Recordset

Private Sub Form_Load()

    Set mCno = New ADODB.Connection
    Set mRs = New ADODB.Recordset

    With mCno
        .ConnectionString = "driver = {sqlserver};" & _
                            "Data Source = SQLDSN;" & _
                            "UserId=reddy;" & _
                            "Password=reddy04"
        .Open
    End With

    With mRs
        .Open "SELECT date, agentid " & _
              "FROM   tsrtime       ", _
              mCno, adOpenForwardOnly

        Do Until .EOF
            Listdt.AddItem !date
            List1.AddItem !agentid
            mRs.MoveNext
        Loop

         If .State = adStateOpen Then .Close
    End With
    Set mRs = Nothing

End Sub

Public Sub Cmdret_Click()

    With mCno
        If .State = adStateClosed Then
            .ConnectionString = "driver = {sqlserver};" & _
                                "Data Source = SQLDSN;" & _
                                "UserId=reddy;" & _
                                "Password=reddy04"
            .Open
        End If
    End With

    With mRs
        .Open "SELECT *                                         " & _
              "FROM   tsrtime                                   " & _
              "WHERE  date    = '" & Listdt.SelectedItem() & "' " & _
              "  AND  agentid = '" & List1.SelectedItem() & "'  ", _
              mCno, adOpenStatic, adLockPessimistic

        If .EOF Then
            MsgBox "No records found for user " & List1.List(i) & " On " & Listdt.List(i), _
                   VbExclamation Or vbOK, “No Record Found”
        Else
            Text1.Text = !starttime
            Text2.Text = !endtime
            Text3.Text = !breaklength
            Text4.Text = !reasoncode
            Text5.Text = !paycode
        End If
        .Close
    End With

    Text1.SetFocus
    List1.Enabled = False
    Listdt.Enabled = False

End Sub

Private Sub cmdSave_Click()

    MCno.Execute "UPDATE tsrtime (starttime, endtime, breaklength, reasoncode, paycode)    " & _
                 "VALUES ('" & Text1.Text & "', '" & Text2.Text & ', '" & Text3.Text & "', " & _
                 "        '" & Text4.Text & "', '" & Text5.Text & "')                      " & _
                 "WHERE  date    = '" & Listdt.SelectedItem() & "' " & _
                 "  AND  agentid = '" & List1.SelectedItem() & "'  ""

    MsgBox " 1 row updated "

End Sub

Private Sub cmdExit_Click()
    cno.Close
    End
End Sub

MCno.Execute "UPDATE tsrtime (starttime, endtime, breaklength, reasoncode, paycode)    " & _
                 "VALUES ('" & Text1.Text & "', '" & Text2.Text & "', '" & Text3.Text & "', " & _
                 "        '" & Text4.Text & "', '" & Text5.Text & "')                      " & _
                 "WHERE  date    = '" & Listdt.SelectedItem() & "' " & _
                 "  AND  agentid = '" & List1.SelectedItem() & "'  ""