I am unable to play any files on Windows Vista even though I have all the proper codecs installed

I have installed Mega Codec V. 1005 on vista but does not play any video. I have followed instruction to re-install it but still does not play any files. any help?
Thanks

Which player do you use?
Does the player show any errors? Or do you just get a black screen with audio playing?

My first suggestion would be to update your graphics driver.

I Use K-lite codec pack mega. It does not show any error and it does not play audio too. Once I play a file it stopped.

Updating your graphics driver will probably solve the problem.

As a workaround you could try:
MPC-HC options > Playback > Output > select "System Default" as video renderer