I have an old snow blower with a 3HP Briggs and Stratton engine. The pull cord suddenly froze up. Any ideas on what to do?

So you can not pull it out at all, right? Try removing the spark plug and tell us if you can now pull the rope.

Hi,
Sorry Bob, no rating available.
Yes, you should check to see if the engine is locked-up or simply hydraulically locked. Locked up means it does not turn with the plug out, and hydraulically means it sprays out oil through the plug hole.
There are "tricks" that can be done with actuallly oil starved engines that do lock. Advise!
Peace,
Clarke

Another trick is to open the oil fill plug to see if a mix of gas and oil shoot out when you turn over the engine, this happens when you have a sticking needle valve