System Restore restores the registry among other things, and this should solve your problem.
NOTE: You will need to re - install any software and updates that you have installed between now and the restore point, but you can use Windows Update for updates.
If the first attempt fails, then try an earlier point or two. Don't forget to check the box to show more than 5 days of restore points. Do you know when this problem started? Try a system restore to a point in time BEFORE the problem started.
