Hi Steve,
First make sure that you have the radio code.
Disconnect the battery - you will need two different sized of spanner.
Wait a few minutes, then reconnect the battery. The alarm will go off. All your settings - clock, radio, sometime the satnav will need the sound resetting, and then the window settings - full one press drop & return - each window individually.
I found it out when we were just about to go Leeds on New Years day and I had to call out Britannia Rescue --- the man did not know anything about modern cars, in his words! My son in law googled it and there you are.
Regards,
Peter.