I had a friend put my brakes pads on and he didn't tieting up the bolts so they fell out, I replace them but now my brake won't work. I bleeded them and still not working

i would bleed the system once again just to make sure that there is not air in it, after making sure that there is not more air and there is not pressure you'll probably need to replace the brake master cylinder. i wonder if the mechanic just compress the caliper pistons because in some cars you cant do that cause you damage the master cylinder. i hope it helps :) let me know