Touchpad not working correctly.

Try reinstalling the driver from HP's support site and see if that helps.

If its anything like the Dell Latitude laptops from my work, the scroll function may have just been unticked/disabled.

In your system tray there may be an 'HP TouchPad' icon or something similarly named. If you go into that there may bea tab or setting in there for scrolling that is unticked.

Its worth checking there.

Try uninstalling it and reinstalling it.

Likely that won't work, therefore you'll need to buy a USB mouse.