Sounds like either a driver malfunction or more likely a failing sound card. Most of the stuff below (Windows & Programs) wouldn't likely be causing problems. I'd be willing to bet it's a hardware problem (due to it only being one side). Figure Out What's Failing
If you're using a secondary sound card Replace Drivers
*** i.e. you have a second built in one on your motherboard, enable that.
If you still hear the sound on a different card, then it's something within Windows and not a problem w/ hardware.
If you don't hear the sound, then it's something w/ drivers or your hardware.
If you don't have an extra sound card, see if you can find/buy one
Download & Install a Program like Guru's Driver Sweeper
Uninstall your sound drivers w/ Driver Sweeper
Download and install the latest drivers for your sound card.
If the sound is still there and you couldn't test a secondary card you're likely dealing with either a hardware failure (most likely with sound only happening in one speaker) or something in Windows failing.
If you want to try to fix windows, you can do the following:Test to see if a program is causing the problem
Run an elevated Command Prompt and run this command:
Peform a system restore
Perform a repair install.
Type msconfig into start menu search and hit Enter
Go to the startup tab and disable everything.
Do you still hear the sound?
Yes -- Not a program
No -- A program is likely causing the problem.
If none of the above helps, I highly suggest that you attempt to borrow or purchase an extra sound card. If you do so through a place like Newegg and it turns out that it doesn't fix the problem, you should be able to return the product. Keep in mind that none of this is exact, you could disable all programs and still hear the sound and it might be a Windows process causing the problem (very unlikely). Or, you could switch to a different sound card and still hear the sound and it might be caused by the drivers for the other card (unlikely).
Good Sound Cards:
HT | OMEGA Series (Striker, Claro)
Sound Blaster X-FI
M-AUDIO Newegg.com Sound Cards
If you're looking for a low budget sound card to replace yours, your best bet is this: http://www.newegg.com/Product/Produc...82E16829102003