The built in mouse has stopped working on ...

Hello,
You could try some of the following things in the order listed that may help you solve the problem you are having with your laptop mouse.
1. Clean the mouse pad extremely well. Sometimes they can get greasy from the oils that occur naturally on our skin and can cause the device not to function properly.
2. Check your BIOS to make sure that no changes have occurred that would prevent the device from working.
3. The device drivers may have become corrupted or outdated. You can check the manufacturer's website for the proper drivers or you can possibly download them from drivers.com, driversguide.com, or mrdriver.com. to name a few.
These suggestions may help solve your problem, but there could be deeper issues that may be causing your mouse to not function properly and may require a technician to repair it.

Good luck and if you would not mind, please rate my help. I would greatly appreciate it. Thank You.