Do you mean that the pointer moves on the screen, but that you can't click on/select things?
You may just need to re-install your mouse/touchpad drivers. Go into the Device Manager (in Control Panel). Go to Mice and then right click, select uninstall. Do for both your mouse and your trackpad. When complete, shutdown. Disconnect your mouse and restart. Once the system is fully restarted, reconnect your mouse and let Windows re-install the drivers.