I've replaced the batteries, rebooted the computer, but the mouse part of my Desktop 3000 wireless laser set won't work. There's no 'reset' button, and I can't find help--the Windows 8 option isn't on the support page of the website, yet the store that sold me the set (Office Depot) said it would work with Windows 8, and it worked fine until the batteries went low (red light came on), and then it just died.

Ensure that the batteries are inserted correctly. In some of the newer Microsoft mice, the batteries are inserted - end first. Check with the inside of the mouse for correct orientation.

OK, when you checked the batteries, did the light show green? If you get no light, the mouse is most likely broken.

If the light showed green and the laser is showing blue or red, it should work. If it doesn't, check for the siting of the transmitter. I have mine attached to a USB extender cable which sits on top of the desk.