The back door on the passenger side of my megane does not open with the central locking, nor does the button pull up from inside, its as if its jammed itself.its happened before with people lifting the door handle before the key fob is pressed, although it has always fixed itself in the past and now l cant get the door open at all.

Any Ideas whats causing the problem (without taking it to a garage who will charge a fortune)

Broken plastic linkage at external handle.
Remove seat. Remove door trim (see Haynes manual).
Reach inside with 10mm spanner to undo outer door handle.
Broken section can be replaced by small nut and lock-bolt.
New handle is another alternative but will require painting.
Individual parts not available separately (scrap yard?)

is the child lock clip on