4 speed auto won't do anything

[Dearlove]

Hi guys.

Car is a 96 c36

Well as the title says. My gearbox won't do anything. The lever still must be connected because it locks it in park. But when selecting any gear it just does nothing.

It happened when I went down to the shops. I reversed out of the car bay and went to put it in drive and nothing happened. Then I couldn't put it and reverse or any other gear. Nothing went bang or clunk and it had been working fine before

Fluid level is good and it's not the pump, the level drops when I start it
Any ideas?