if you are only having problems playing audio through webpages, then the webpages you may be visiting may be require a different plug-in (real player, quicktime, etc).
there is no way that your headphones could be the reason you are only able to play wmp files, what program are u using to play your other files. what other file formats are you trying to play mp3? mp4? ogg?
and how/when did the problem start occuring, any software/hardware changes that you can recall that may have instigated this issue.
My sound card is working my speakers are plugged in correctly i think and one of my earophones is broke could this be the reason that only wmp files play and songs on webpages dont because i really need to fix this problem can anyone suggest anything ?