It sounds like your lockstrip is broke and will need replacing so before you open your door you will need a replacment lockstrip or be able to get one on the day you open it,was your door hard to lock for some time?if so your door will need re-packing so you dont break the new lockstrip.to open try and force the handle down to open possition and some open but like I said once opened it the lockstrip wont lock again so make sure you have a new one to replace it with.feel free to contact me through my website with any more questions about thisproblem.
shaun www.sdwupvcrepair.co.uk
July 2008