I am writing a class that manipulates the request object.
But how to get the request object when invoking this method?

I have a function

public static string getSomething(object sender){
 return ((Request)object).ServerVariables["SCRIPT_NAME"];
}

The above method won't work when invoking from an object of Page.

Any clue?

you need to use HTTPContext:

HttpContext.Current.Request.ServerVariables [" .. "];