If your brakes have seized, this means that they have locked and are engaged on the bike, or they are partially locked and the bike is very hard to roll. The first step is determining whether it is the front or the rear. To do this you can put the bike up on the center stand, and try to roll the wheel by hand once it is in the air.
When you have determined which wheel is seized, it is time to service it and try to free it up.