Lost the sound and volume, Making everything worse. Desperate for help.

My main problem is I have some how uninstalled the sound and volume. I am also very uncomputer savvy.

I uninstalled what I thought were useless things, obviously not as immediately lost the sound and icon. Can't restore, won't work. Devise manager doesn't recognise.

I actually have made several mistakes. Computer is very very slow. Keeps coming up with end now. Google not coming up as usual server, not sure using the right word. Now have msn messaging coming up as well as bing.

Also managed to do something with the resolution and cannot reset either.

Any help, in simple terms, especially to restore the sound most appreciated.