Laptop touchpad won’t work

Operating system not responding
Try pressing the Num Lock or Scroll Lock keys on the keyboard to see if any lights on the keyboard turn on or off. If the lights remain on or off after pressing the keys several times, then the computer is likely frozen. Restart the computer to see if this resolves the problem and results in the touchpad working again.

External device
Some USB and PS/2 input devices automatically disable the touchpad when you plug them in. As a troubleshooting step, turn off the computer, disconnect all external devices, then start the computer again to ensure one of them has not turned off the touchpad.

Check mouse settings
Enable touchpad in the Mouse Properties in Control Panel.

Checking Device Manager and updating drivers
Locate the touchpad in Device Manager and right-click the icon then select Update Driver Software.
Tip: Right-clicking the touchpad icon gives you the option to either enable or disable it, depending on the device’s status. If disabled, re-enable and test the touchpad. If it is already enabled, change it to disabled, then re-enable it. Sometimes toggling this setting “reboots” and fixes the touchpad.

Check CMOS (BIOS) setup
Make sure the touchpad has not been disabled in the CMOS (BIOS) setup.

Corrupt operating system files
– Use a restore point that is at a date and time prior to when the touchpad stopped working, or
– Perform a checkdisk on the system partition, or
– Do an operating system repair, or
– As a last resort, reinstall the operating system.

Defective hardware
Finally, if the touchpad still is not working correctly or at all, you may need to take the laptop to a computer repair shop for service. It could require replacement of the touchpad itself or another hardware component. If the touchpad cannot be fixed, connect and use an external mouse as a workaround.

Source:
computerhope.com/issues/ch001497.htm