And that is why you shouldn't go messing around in services unless you're 100% certain of what you're doing.
First off... What OS are you using? NT? 2000? XP? Vista?
You probably killed a service that controls USB, and the touchscreen is USB, right? After you set all the services back to their defualt settings, did you restart those services and/or reboot the computer afterward? The services aren't going to automatically restart when you set them back to "automatic".
As a last resort, you could re-install Windoze. That would suck, but you can chalk it up to lessons learned.