95 neon caliper lockedup

my niece bought a 95 neon in fair condition, it needed brakes, a friend atempted to do them and ended up replacing the driver side caliper. The wheel started to smoke real bad so I had her bring it to me to look at, i pulled it apart and i cannot retract the piston on the new caliper and the rotor is toast. Could it have been the rotor being too thin and the piston came out too far and froze? I plan on replacing the rotors but is the caliper wasted also or is there a problem maybe in the master cylinder??? help please.

I have seen cars with a bad or kinked brake hose cause that.

I ended up removing the brake line from the caliper and the piston retracted fine, so I applied pressure to the pedal and barely a drop came out. I then disconnected the steel line and depressed the pedal and plenty of fluid came out so the flexible line was colapsed, I replaced it and the rotors and the car stops prefectly. Thanks for all your help.