Windows 7 lost sound on my computer

Hello
ive lost the sound to my headphones on my computer
ive tryed using another pair of headphoes and they worked-ish i get no bass out of them...
ive tryed uninstalling and reinstalling all my sound drivers that didnt help much...
ive even reinstalled my OS and that did nothing
anyone got some other ideas?

If it's a desktop a PCI sound card, if a laptop ????

it is a PC with Win 7 64x