Q: Do I Need to reset the timing when the Serpentine belt breaks?

Loosing the serpentine belt should not affect the engine timing. But it sounds like you have some other problem. The first thing that comes to mind is that the harmonic balancer may be coming apart. The harmonic balancer is a three piece front pulley that sometimes separates at the joints and wobbles around. It can cause you to loose a serpentine belt.You should have this checked out before you drive the car any more to avoid being stranded. You can have it checked at your convenience by contacting YourMechanic. They will send a technician to your home or office to check out your knocking noise and let you know what is going on and what it will take to fix it.