Trackpad "Tap to Click" not working

Hello,

Somehow on the Trackpad settings, the "Tap to Click" on the One Finger section was unchecked.

Thus, the only way I can use my computer is by right clicking everything but I have no way to solve this problem by re-checking the "Tap to Click" box because I would need that box to be checked in order to do that..

Is there an alternate way to get that box checked?

Thanks alot,

Marco