Windows 7: Audio Service Not Running/No sound/No speakers/Realtek problem

I'm hoping someone can help me.I'm working on a custom pc that my brother built for me. The specs are in my signature.

I recently upgraded from 32 bit to 64 bit Windows 7 home premium (I know it's not the best, but it's what I could afford). I did a drive reformat also. Initially, everything was fine. But for some reason all of a sudden, I have no sound, my plugged in speakers are not detected at all and the audio service is not running. Everything else is fine. I assumed it was as a result of an update, so I did a system restore. I guess my restore points didn't go back far enough. No change.

-According to my motherboard specs, I have the realtek ALC888 onboard audio. So, I thought I'd just be able to install the latest hd audio driver for my os from realtek's site. I tried several times (10+). It prompts me to restart and when I do, it says that the device driver did not install correctly and it defaults to the microsoft one every time.

-In device manager, I have a yellow triangle next to one of the 2 "high definition audio controllers" with a code 10 error (device cannot start). Under sound, video and game controllers, I have "High definition audio device": microsoft, driver version 6.1.7601.17514 11/19/2010.

I have seen a few of these realtek problems in the forums, but i haven't found anything that has worked for me. I tried manually installing the driver from the zip file by directing the update utility to it's extracted location. It always says that my driver is up to date. I'm not sure whether I'm supposed to be updating one of the hd audio controllers or the hd audio device or both (I've tried both), so I suppose i could be doing it wrong. I've tried uninstalling the hd audio controllers and the hd audio devices and rebooting, the same thing happens.

I've tried a repair install from the disc. No change. The only thing I haven't tried is reformatting my hard drive and doing yet another clean install. I really don't want to have to do this again because re-downloading my programs and music/docs/pictures is a chore. So, I'm asking if anyone has any idea what else I can do before I go to the last resort?

Thank you for your time

**completely reinstalled windows and still don't have any sound...I'm completely at a loss.

Try the previous Realtek driver 2.67 or the Asrock 2.31 driver.
Download Realtek High Definition Audio 2.67 Vista 64 - Technical Details - FileHippo.com
ASRock > Products > Motherboard > G43Twins-FullHD > Download

I'm kinda winging this, so I uninstalled the high definition audio controller with the yellow triangle, then installed the .exe file from your asrock link. On reboot it says that the device did not install properly

when i run the "fixya" application after trying the above remedy, I get the following results and there's still the yellow triangle next to one of the hd audio controllers in device managers
hardware changes might not have been detected
high definition audio controller has a problem

Does it make a difference that before all this happened, my speakers (which i've replaced because i assumed they were broken) seemed to become quieter at max volume and then started crackling and producing very loud static? perhaps not, i have no idea.

try uninstalling the audio drivers and install again it worked for me.

I've uninstalled everything and installed the hd audio driver - when i reboot as prompted it says the driver did not install correctly.