Solved Sudden loss of sound.

Hi. Just found this forum while looking for some assistance for a problem that has literally occured overnight. I inherited this computer from my son after he moved on to a new one.I am not exactly a computer noob but certainly no expert either. I have been using the computer for about 6 months with no problems. I was using it late Saturday night and there was nothing wrong with the sound. I turn it on and fire it up Sunday morning to see the speaker icon on the Taskbar has a little red cross along side it and a box telling me 'No Audio Output Device is Installed.' I found this forum and started looking through it trying everything recommended.I tried System Restore but that made no difference. I tried the Windows Help with the option to automatically fix the problem but it didn't. If I go into Control Panel...Hardware and Sound...Sound...Manage Audio Devices, I get a box with Digital Display Audio,AMD Audio Device,not plugged in.If I right click on this I find 'Show Disabled Devices' and 'Show Disconnected Devices' both ticked. I'm pretty sure I used to see a Realtek icon on the Taskbar but there is'nt one there now although I do have a Realtek folder in my Programs but there is no exe file in there? Anyway I would be grateful for any advice or suggestions you could give me.
Regards and thanks in advance.

Well I reinstalled the Realtek driver and everything is working now,