Bad Image Error after a damaged .dll file

I’m having problems with a damaged .dll file. Until now, I noticed that the Windows Photo Gallery as well as Winamp is already affected. I tried opening Winamp and I received an error posted below:

C:Windowssystem32WindowsCodecs.dll is either not designed to run on Windows or it contains an error. Try installing the program again using the original installation media or contact your system administrator or the software vendor for support.
How can I establish a resolution? Help!
