Sideways

I use itunes for my ipod and on Wednesday it said there was an update available so as usual I installed it. Anyway it wouldn't run. So I did a system restore to try and remove it and it didn't work as it said there were files missing. So I then reinstalled itunes and it says application wont run because it has detected a problem with my audio configration.

Can anyone advise me what to do I've done system restore 3 times and I can't get it back to normal.
Any help would be much appreciated