Yes. I think you want "vbCrLf"
That is the vb
reserved name for "Carriage Return, Line Feed" (remember typewriters?!)
So it looks like you are taking the current value, appending your new data, and then pushing the concatenated value back in, which is the way to go. So like this:
txtComments.Value = cmbRep.Value & " " & Date & " " & Time & " " & txtNewComment.Value _
& vbCrLf & vbCrLf & txtComments.Value
Did that work?