Do I understand you opened the bleeder screw or loosened the flexible hose, and then even a c-clamp won't do it?

I used a bar clamp, a C clamp also. i failed to mention that the inside of the disk was worn to the ridges,, the face was as thin as a match book cover. i accidentally punctured one of the boots and just replaced the whole caliper. when i took off the brake line and the caliper it went back in but the boot was torn, it would have gone back in if i took it off and didnt tear the rubber boot

I'm confused. That boot is just a dust boot and will not prevent the piston from going back in. What CAN happen is if that boot was torn previously AND you have steel pistons, water can get in there and cause the chrome plating on the piston to lift, and rust spots form underneath it. That definitely will make it almost impossible to get the piston back in or out.

So are you saying you installed a new caliper? If so, did everything go back together properly or are you still having trouble?