the front brake caliper on car is not releasing.

Sounds like a seized caliper. Assuming they were reinstalled correctly with all the bolts and guides cleaned and operating freely, the piston inside the caliper bore is quite likely binding. This happens because the new pads cause the pistons so sit deeper into the caliper bore in an area that may have become corroded from moisture in the system. Calipers are not usually worth servicing and should be replaced with new ones when this happens.