ALI_6_ :
I installed window 8 64bit yesterday, previously i had window 7 pro 32 bit.i had builtin speakers but when I installed window 8 there was nothing in device manager.
That's an entirely different issue. Go to the manufacturer's website and download the WIndows 8.1 x64 drivers for your system. If they do not have drivers for the system (unlikely), you can try the Windows 7 x64 ones.