i have an 85 735i e23, i dont know if i need new calipers or what, my rotors are bent out of shape so every time i push on the brakes they start to rumble, but the reason it happend was because a piston in the brakes or something got stuck? im not sure but i think thats why, so now i dont know what to do

Does the car stay straigt wile braking? if it starts turning corners then you have a brake problem.
Put the car on a jack and see if one wheel turns more heavy then the other , that would be the side where the piston is stuck.
You could try to make it move again by letting somebody press the brakepedal while you use a big vice or something to push it back in ( don't let it come out too far ) , but you be better of by rebuilding the calliper or buy a rebuild one because if it got stuck one time it will be stuck again because of the dirt/rust being in there allready

Generally if its a caliper u should replace them in pairs, the frt's are 4 piston and trying to free them up only works for the short time, recommended because u can getting pulling when braking due to one caliper is working better than the other, but it is only suggested. Based on the braking pulsation you may need rotors, do a run out measurement and see.

ok thanks, yea its both the calipers and the rotors, my dad says its still ok mainly because hes lazy and doesnt want to fix it and is saying new calipers will be 300 each (dont believe that) but i already have new rotors and pads, im not sure where online would be a good place to get calipers from, i see allot of aftermarket ones but i dont want to gamble with the brakes of a 4200lb car lol, so you guys know any good sites to get new calipers from? p yea and the piston on the caliper is rusted, rather just get new ones than try and pry those free just for it to lock up again