SOUND PROBLEM

i hav an assembled PC. motherboard - asus, monitor - aoc, windows xp
I hav few problem with my PC i.e. viruses was there.
I formated my PC after that i found that ther is no audio driver installed.
I try to reinstall this driver but it says that installing RLTK HD audio driver faluire.
I tried some other drivers to install but was unsuccess.
Now i m in trouble how to solve this problem.
PLz help me as soon as possible
thanking u
With regard
Rohit Gupta