1) If your mouse came with any 3rd party software, then uninstall this first via "Add/Remove Programs" from "Start" > "Control Panel". If unsure, check the brand of your mouse (for example logitech or microsoft) and see if there is any installed software that looks as though it's to do with your mouse. If your mouse is unbranded, there probably isn't any 3rd party software installed.
2) Go to "Start" > "Control Panel" > "Performance and Maintenance" > "System," then open the "Hardware" tab and click on "Device Manager." Expand the list of devices under "Mice and other pointing devices," then double-click on your mouse.
3) Click to open the "Driver" tab, then click on the "Uninstall" button at the bottom of the dialogue box. You will now be prompted to confirm the operation. Click "OK" to continue. The uninstallation process will now commence. Unplug your mouse.
4) Reboot your pc. When it restarts, plug in your mouse, and Windows should automatically check for the correct driver.