Sound windows vista home premium 32 bit service pack 2

For some reason,the sound on my dell inspiron 1525 has erm,,,,gone.
My volume controls are all set to full,when playing music on my internal cd player the volume control risers and falls as it plays.

I did a speaker test and received the left and fight bleep.I went to device manager and clicked sound and videocontrollers,Intel(R)hdaudio HDMI working correctly,and Sigma Intel HD Audio Codec working properly,no conflicts seen.

I have tried connecting to a tv by HDMI cable tried playing youtube music,no music on either device.

Struggling a bit now....any help would be appreciated.....

Finally,I would have tried to system restore but can't, error code Ox8004230F....I wondered if ther could have been a connection......but let's look at the sound first...?
Unless you guys and dolls out there no better than moi???

Melvyn