Mouse

Symptom: Mouse appears and you can move it on the screen, but you can't click.

Solution: In Control Panel/Mouse check the Double-click speed. It may have a bar turned all the way to the right and that makes clicking impossible. To get into Control Panel without being able to click you will need to hit Control and Escape keys to activate the Start Menu. Then use arrow keys, enter key and tab keys to get into the Mouse icon and make the change.

Symptom: Mouse appears dead (will not move or click).

Solution: Change over to a known working mouse on that machine. If the second mouse works then take the first mouse to the second machine and see if it is still dead. If the first mouse fails to work on the second machine then you probably have a bad mouse.

If the known working mouse from the second machine fails to work on the first machine and your first mouse works on the second machine, then you have a hardware connector or software problem on the first machine.

Doublecheck the software on the first machine. Look in Device Manager to see if a mouse is identified. If it isn't try redetecting it in Control Panel/Add Hardware.  If that fails check in the case to see if the mouse serial port ribbon cable has been dislodged.