Using Windows Vista. It worked fine yesterday. First of all, when I try to play any song, it puts a red X next to it and says it cannot play file, and that there may be something wrong with my sound driver. Well I checked my driver and it says it's working fine. Second thing is, I can't get any media (or sound) to work from the internet. When I go to Youtube.com (for example), it will play the clip, but the entire web page and whatever's playing will be very choppy with no sound, sometimes eventually freezing internet explorer. What in the world is going on here??
Please HELP!! I need my media back!!

could be malware related, but I would try going to either the manufacturer of you motherboard (if you have onboard sound) or the manufacturer of your sound card and download the latest drivers to see if it fixes your problem

Windows always says this device is working properly

( because i delete a file by mistake) i do this before and fix
start-my computer-hard disk drives and options(usin the last button of your computer mouse)-tools and them i click in backup
also before you do anything ,read more about this option in your
help and support center search backup
(sorry my english in not good)

Well I just did a system restore and that seemed to fix the problem.. thanks for your help though!