i wouldn't listen to this plonker, he obviously hasn't got a clue a bit like yourself really. You definately need a locksmith and by not using one could cost you a new door. By the way a new door will probably last about 5 mins judging by the std of todays "fitters". I dont know how you managed to remove the cylinder either because the "black thing in the middle" aka THE CAM is normally offset (in other words partially turned) and the screw that holds it in place is on the edge of the door so is inaccessible if the door is locked. Anyway dont be a fool, you dont know what the hell your doing so call an expert and yes it may cost a lot money but a new door will cost considerably more. Also when looking for a locksmith look for a smaller company not a big maintenance company as it will be cheaper.
Sean - Locksmith and Specialist in UPVC Doors, August 2007