you will probly have to take the seat out and fix it.
easy cheap not done right fix= put a bolt with a big washer through the floor from the bottom of the car and bolt the seat back doun and probly fix it again anyway in a few months.
Right way= pull seats out along with carpet and patch or even replace floor pan. Install new seat stud's and reinstall carpet and seats.<---- not as easy as I made it sound lol.
car has no carpet or seats ... how would i put a bolt threw the botom with a big heavy washer if the stud is still broken in the floor?..i started drilling it out today and found some "easy outs" in my garage all to big tho .. illl head the harware store tomorow and let ya no how it works