how to write URDU

Question

Im trying to write Urdu in richtextbox in C#.i tried this by mapping each keyboard character to urdu letter(unicode). but the problem im facing is that : itz printing both charcters i.e. the pressed key(eng) & the corresponding urdu character.i did al that procedure on key Down event.

one of the solutions that i found was to set the system locale at runtime to either Urdu or Arabic.but it isn't wrking.

plz can anyone help me to do this...

regards
AArif.