How to fix no audio/sound in Windows 7?

I installed Windows 7 Ultimate 32 bit from Windows XP and I have no sound/audio.

I tried everything: installing realtek drivers, browsing youtube, i googled it, tried the audio troubleshooter, but nothing happens.

In the Manage Audio Devices window, in playback tab, there seemed to be no speaker listed in there if you click on Show Disabled devices but I’m pretty sure I have speakers connected. It was working fine when i was on xp but now it stopped working.

My computer says that the device is working properly and is up to date but still no sound.
Help please?