Help! Rear brake help needed asap!

Took the rear wheel off to change the brake pads and the caliper is knackered! The piston has popped out. May be easier to buy a new caliper but I need to know how to disconnect and reconnect the hand brake cable. Any help asap please as need to sort this tomorrow. Thankyou. xx

You need to slacken the cable adjuster under the console behind the handbrake , then the outer cable will pull out of its socket on the caliper and the inner just hooks off the lever on the caliper

Have you tried winding the piston back in? Even with the pads down to the metal it shouldn't allow the piston to come out far enough that it comes off the thread it's on.