You can try and locate the Fn key and the key that turns on your mouse pad, once finding that combination hold Fn and toggle the enable key " usually one of the numbers or the F# keys. If that does not work you might need to reinstall the device drivers, I am unsure your Windows operating system but you may want to grab an external mouse for this. Go to Devices manager, If you do not know how here is a universal pathway, " Control Panel - Administrative Tool - Computer Management - Device Manager " Once there find your device and uninstall the drivers " you can also try enable and disable first ", Once uninstalled restart your computer and Windows will discover the pointing device and reinstall it shortly after start up, you may need to go to though the add new hardware wizard when installing but this is the best solution I can think of.

Try to add an external additional mouse that will resolve the issue temporarily or else re install mouse pad drivers , if that also doesn't work you may need to check with acer for replacing the same.