The S-Belt on your 2000 Chevy Monte Carlo broke and upon inspection it appears the flywheel pulley is pushed out of alignment with the rest of the vehicles pulleys What would cause this?

I would first check to see if the bolt(s) holding it in place are loose; that is what you want it to be. I am adding my own personal experience to this persons answer.We have a 1998 Monte Carlo and were having the same problem over and over again till we finally found a mechanic who finally found the problem.It was the harmonic balancer and we had it replaced for about $400. and now everything fine.