m15, touchpad not working as expected?

After a period of use on my alienware m15, my touchpad stopped working as expected. It still tracks, but lost all the gestures. I believe it's suppose to came with windows precision driver, but the touchpad settings did not show anything about precision touchpad but only one option which is touchpad sensitivity. The main problem is all gestures failed to work even the basic scrolling. I have tried to go to device manager to see if anything shows up,but there is no touchpad in mouse pointing system section. And I also failed to find any driver related to alienware m15 driver on dell website. Have no idea how to fix my touchpad to get my gestures back. Would be glad if anyone could help me to solve the problem, thanks.