Resetting Controls

[Dont mind reading] I was starting to load up the game, and none of the servers where popping up. I had started to click around, and my controls got messed up. The servers had loaded fine after a few restarts, but my controls are still messed up. How do you reset the controls to original setting? Because when I go to play “Mouse 0” appears for about 10 commands, and I can not “unswitch” it back.

[Dont like to read] How do you reset the controls?

Thanks a lot!