it sounds like its your latch thats not releasing,try and force the door towards the hinges and might release if not de-glaze door(if you know how)and try again,once opened you will prob need a new lockstrip,you can order one from north west hardware website,but as a quick fix,the latch sometimes has a screw you can unscrew and take lach off so you can use door untill you can get a replacement.hope this helps
shaun www.sdwupvcrepair.co.uk, July 2008