Best answer as chosen by user BudVitoff: Use System Restore

This is the perfect example of when System Restore will save the day. Click Start -> All Programs -> Accessories -> System Restore. Click the box that says show more restore points, and pick a date prior to when you made the change. In the future remember that there's no undo for changes you make in the Control Panel!

When you've gotten your system back like you want it, I urge you to get yourself an external hard drive and a good 3rd party backup program. You can set it up to do everything automagically at the time and frequency of your choice. 1 TB external hard drives are about $70 these days and a really good FREE backup program is the Easeus todo backup free which you can download from
http://www.todo-backup.com/products/home/free-backup-software.htm . That can save you a lot of time and frustration the next time something like this happens. Sooner or later it happens to all computers for one reason or another.

Good luck.