door won't stay shut fully

Hi all - Today, after washing the car, the driver's door shut suddenly felt different and the door won't stay shut fully but only on its safety catch; unless I pull the door very very firmly from the inside. Once shut, the door handle won't open the door, although the doorhandle mechanism is still functional. There's nothing amiss with door rubbers etc - What's up? is it the door latch?

I'm guessing you can't just replace the spring?