When you use a preceding @ sign in C#, that means escape characters won't work. You can then write backslashes freely.
For example, @"C:\Documents and Settings\rashakil\My Documents\serkan love files" would be a valid string literal. If you want to write a double quote character in such a representation, I think (but you should double check that) you can write it by writing two double quote characters: @"blah "" hah" == "blah \" hah"
For Each ctrl As Control In Me.Controls("pnlMainPanel").Controls
If ctrl.GetType Is GetType(System.Windows.Forms.Panel) Then
For Each subCtrl As Control In ctrl.Controls
If subCtrl.GetType Is GetType(System.Windows.Forms.TextBox) Then
If subCtrl.GetType Is ...