You say it doesn't work. Have you checked the batteries? Are they new and are they installed correctly? Have you checked the USB connection, switching USB ports in case the one you are using is bad? Have you pushed the "connect" button on the bottom of the mouse to connect to your computer? If you have completed all these steps, I would then go to the device manager and search for mice or human interface devices. If you find the mouse there, uninstall it and let the system find it when it restarts.
Answers & Comments
You say it doesn't work. Have you checked the batteries? Are they new and are they installed correctly? Have you checked the USB connection, switching USB ports in case the one you are using is bad? Have you pushed the "connect" button on the bottom of the mouse to connect to your computer?
If you have completed all these steps, I would then go to the device manager and search for mice or human interface devices. If you find the mouse there, uninstall it and let the system find it when it restarts.