First, try moving your computer to a flat surface to make sure the ventilation is not blocked. If that does not work, you should clean the internal fan, this will require some disassembly. The last thing you could try is replacing the heatsink thermal paste.

There are three main causes for this. The first being that it is disabled. The easiest way to enable the touchpad is by using an external mouse and going to Control Panel > Mouse > Settings > Enable. Build up on the touchpad can also cause it to not respond. Simply power off the computer and wipe down the touchpad. If this is not the issue, the touchpad may not have properly started when the computer booted. The solution is to reboot the computer and do not touch the touchpad until the computer has completely booted.