Hello FIJO FRANCIS T,
I am not sure if your question is directly related to RadControls for WinForms. Could you please share which is the RadControl you are using?
The provided link in this thread should actually point to:
http://www.telerik.com/community/forums/winforms/combobox-and-listbox/how-to-restrict-user-from-entering-text-which-is-not-in-a-display-member-of-combobox-items.aspx
A bit off topic, please note that if you have urgent issues that require quick responses from us, you have to submit a support ticket from the licensed account. This is so, because support tickets are reviewed and handled according to the license that you have.
All the best,
Nikolay
the Telerik team
Q1’11 SP1 of RadControls for WinForms is available for
download; also available is the Q2'11
Roadmap for Telerik Windows Forms controls.