Mouse help?

Help! I need a mouse, I mean, really. I hate the touchpad. But my mouse isn't working-- suddenly.  Here's the scoop:

Rebooted.
Put another battery in mouse.
Tried another mouse.
Tried all the USB ports.
Flashdrive worked fine in all USB ports.
Tried mouse in another PC and it worked fine (not mouse problem).
Reinstalled drivers.

I did all the troubleshooting and stuff, and nothing worked. I thought it might have something to the function key F9, so tried to toggle that, and nothing happened.

Device manager doesn't list the mouse, just the touchpad, now.

Any thoughts? I am pretty sure it's just a setting issue, that I inadvertently switched something off or on, so I'm really reluctant to spend $70 to have the tech keep it for a week and say, "Oh, you just needed to press Ctrl something."

Windows 7. Computer is about 2 years old, no problems.

Help! Any ideas?

Alicia