Tools required: Torx 6 screwdriver, plastic tool such as a credit card or guitar plectrum.
First remove the battery cover, battery, sim etc. Now run something like a guitar plectrum or the edge of a credit card around the join of the front cover in order to release it.
You can now remove the front cover and keypad.
You now have access to a ribbon connector. The connector attaches like a plug and socket. Lift the connector away from the phone to unplug it. The LCD screen will now be free and can be replaced. Reverse the procedure for reassembly.