Window motor regulator has gone bad. It is the track that the window itself attaches to, and the cables that raise and lower the window that come off of the pulleys or snap not allowing the track to raise or lower
There wouldnt be a plastic part connected to your exhaust system. The exhaust temperatures can get very hot which would melt plastic pieces. The closest thing would be a rubber hanger that holds the muffler up to the car, which would simply be called a muffler hanger, any parts department...