An Audi Q3 owner 2012 model from new. We had this problem just this week of drivers door not opening from the outside, but from inside fine.
Courtesy of a (fairly time consuming) google search last night I found an easy potential solution that works not only on Audi's it said.
So I tried it this morning.... and hey presto - worked first time...brilliant so many thanks to the poster on that thread
"You have one person on drivers seat, one person outside drivers door - you time unlocking manually from the inside at exactly the same time as the person outside pulls the external door handle - door opens then slam the door shut with some force"
Worked a treat - for how long I don't know, and I don't claim to understand why - but something to do with nudging an exterior handle ratchet of some sort.