try to turn the motor over by hand. if the engine is seized up it would be bad to pull start it. if you find the engine is seized, fill the cylinders with vinegar. this will dissolve rust. let it soak over night and try to turn it by hand again. once it is free, drain the oil and leave the plug out for a while to let as much of the vinegar drain as possible. it takes a little bit for the vinegar to get past the piston rings. then refill the oil and try to start it.

i have restored several antique tractors that had been sitting in fence rows for thirty years this way.