Stuck in 4 th gear

[Bigfellabuck]

Hi all, new to the forum so thanks for the add, I've got a 2004 Touran 1.9 TDI with 168K on it, driving yesterday and dropped down to 4th thru a village and started accelerating and gearbox would not come out of 4th, no noises rattles, bangs, whines or any warning at all previous, any ideas please?
Many thanks Rich, Hull.

Checked cables today, all intact so maybe internal issue??