2001 A3 Passenger door won't open from inside but will from outside?

Hi all,

As the title suggests, my girlfriend's 2001 A3 passenger door won't open from the inside but will from the outside. Could this be some sort of child lock problem, please?

Any advice very much appreciated!

Update: I see that the door handle on the inside of the door sticks out slightly and when I 'pull' it, it doesn't seem to feel as if it 'catches' anything?

Can I buy replacement door handles?