I have a manual 5 gears Audi A3 late 2010.

I was driving on the motorway the other night when all of a sudden I could not change gears.

I had to slow the car to a stop and stopped by the side of the road and it was not possible to put the car into any gear at all.

After about an hour of waiting for the mechanic to turn up, when he arrived he managed to put the car into gear without any issue, so assume something had cooled down?

Is there an issue with something heating up in the gear box somewhere?