You did not mention any additional information about your problem except replacing shower door.However use basic hand tools to complete the job.
Try this following general steps :-
1. Remove the doors by lifting up on one door at a time and then pulling each out. The top of the door has rollers attached to it, and the rollers rest on the inside of the top rail of the frame. Set the doors aside.
2. With your drill, remove the two screws on each end of the top rail, located on the inside of the shower frame. Then lift off the top rail of the shower frame.
3. Use your box knife to cut the caulk on the side and bottom rails of the shower frame. Shower frames are caulked on the outside where they meet with the walls and floor of the shower.
4. Use your drill to remove the screws from the side rails. There will be two screws on each rail, securing it to the shower stall. Then, take the rails out. Remove the screws from the bottom rail and take it out.
5. Use your tape measure to measure the old side rails, top rail and bottom rail. With a pencil, mark the lengths on each new rail. Use your hacksaw to cut each rail. Hold a side rail in the exact location where the old rail was located. With your pencil, mark the screw holes on the shower wall. The new shower frame screw holes may not line up with the old shower frame screw holes. Use your drill and 3/16-inch drill bit to drill new holes if necessary. If the shower walls are ceramic, use the concrete drill bit. If the shower walls are fiberglass, use the multipurpose 3/16-inch drill bit.
6. Insert the 3/16-inch anchors into the holes that you drilled. Put the side rail into position and insert the screws into the holes. Use your drill and Phillips head drill bit to tighten the screws. Place the bottom rail into position and mark the holes. Drill new holes if necessary and install the anchors. Insert only one screw at the end where you installed the first side rail. Lift up the loose end of the bottom rail and slide the second side rail into place. Mark the holes. Remove the side rail and drill the new holes using the 3/16-inch drill bit. Insert the anchors and put the side rail back into place. Insert the screws and tighten with your drill using the Phillips head drill bit.
7. Set the top rail directly onto the side rails. In each end of the top rail, insert the two self-drilling screws until the top is secured to the sides. Insert the tube of clear caulk into the caulking gun. Cut the end off of the tube with your box knife. Caulk the side rails and the bottom rail to the shower walls on the outside of the shower. Re-hang the shower doors by lifting each door and placing the rollers on the inside of the top rail.
Also giving you some links from where you can find a detailed information regarding replacing shower doors.http://www.diynetwork.com/how-to/how-to-replace-a-shower-door/index.htmlhttp://www.thisoldhouse.com/toh/how-to/intro/0,,214441,00.html
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