what has happend is that the handle on the door was stiff as i have pushed it up to lock it something in the door has cracked now the handle moves but not the latch i have had to force the door open and now need to get the lock out so i can try to change it
sounds like the gearbox has broken on your multi lock sometimes the gearbox can be be replaced, you may need a locksmith to take out multilock and check
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix windows and doors.