Since you didn't give us any details of the motor size or brand here is a generic answer. I'd say the key on the flywheel is broken or twisted due to the sudden stop. An easy repair most of the time. Take off the motor top cover and any other shields to gain access to the flywheel. Pull the spark plug out. You will have to rent or buy a flywheel puller for that motor and pull off the fly wheel. The bent or broken key then gets removed and replaced. This is a good time to clean the flywheel and magneto surfaces with light sand paper or steel wool. After installing the new key and original flywheel, set the gap at coil at 0.10" ( that gap is what most small gas engines are set at. consult the manufacturer's specs to be sure) put everything back together and give it a pull. I doubt that the crankshaft is bent because carpet is not as sudden of stop, like hitting a pipe or buried stone or tree stump. You can google the repair manual pdf for all the specs. Good luck.