Are you from GB or Ireland? In the US the boot is called the trunk, (I am Irish).Get a friend to operate the the central locking switch or operate the lock/unlock button on the remote why you listen to the rear door to see if you can hear the trunk (boot) door lock actuator operate, If it operates perhaps a linkage has come off either way the rear door trim panel will have to come off to examine what is wrong. If the motor is not heard to operate you will need to trace the wiring to see what is wrong. Autozone have some popular workshop manuals for free on line once you register (for free) on their website http://bit.ly/autozone_repair_info or there is a company that independent auto repair shops "buy" their information from that offer a very reasonable service to do it yourselvers. You can get a one week subscription or year subscription very cheap. The information is year make and model specific repair procedures, service bulletins, component locations, wiring diagrams ect.... great quality information same as the professionals have ,much better than generic workshop manuals from parts stores, much cheaper than the factory manual try http://bit.ly/mitchell_repair_manuals_online
and get an online repair manual subscription.
thank you very much,I will try it.