Mouse pointer is not moving
Check that the mouse is plugged in
If you have a mouse with a cable, check that it is firmly plugged in to your computer.
If it is a USB mouse (with a rectangular connector), try plugging it in to a different USB port. If it is a PS/2 mouse (with a small, round connector with six pins), make sure that it is plugged in to the green mouse port rather than the purple keyboard port. You may need to restart the computer if it was not plugged in.
Check that the mouse actually works
Plug the mouse in to a different computer and see if it works.
If the mouse is an optical or laser mouse, a light should be shining out of the bottom of the mouse if it is turned on. If there is no light, check that it is turned on. If it is and there is still no light, the mouse may be broken.
Checking wireless mice
Make sure the mouse is turned on. There is often a switch on the bottom of the mouse to turn the mouse off completely, so you can take it with you without it constantly waking up.
If you are using a Bluetooth mouse, make sure you have actually paired the mouse with your computer. See.
Click a button and see if the mouse pointer moves now. Some wireless mice go to sleep to save power, so might not respond until you click a button. See.
Check that the battery of the mouse is charged.
Make sure that the receiver (dongle) is firmly plugged in to the computer.
If your mouse and receiver can operate on different radio channels, make sure that they are both set to the same channel.
You may need to press a button on the mouse, receiver or both to establish a connection. The instruction manual of your mouse should have more details if this is the case.
Most RF (radio) wireless mice should work automatically when you plug them into your computer. If you have a Bluetooth or IR (infrared) wireless mouse, you may need to perform some extra steps to get it working. The steps might depend on the make or model of your mouse.