It sounds like a problem with the multi-function switch on the bottom of the selector lever, or the interlock solenoid (incorporated within it) which stops you moving the stick without the ignition on. If you switch the ignition on, can you move the stick out of Park and in to Neutral? If not, it is probably the solenoid not releasing. If I remember correctly, you also have to press the brake pedal to shift out of Park. Do the brake lights work? (Having said that, it isn’t a conclusive test, as there are two sets of contacts in the brake pedal – one for the lights, and one for other devices like cruise).
Have you tried switching the ignition on and off several times whilst waggling the lever? If the solenoid is working, but sticking, it might be enough to release it. If you can get it into Neutral then the car can at least be moved.
Another thing you could check – is fuse E1 OK? It supplies the power for the shift lock solenoid. If it had blown, then I would expect other things not to work though. There is also a possibility it could be a faulty ignition switch – quite a common problem. One of the contacts feeds fuse E1. However, if you haven’t experienced any electrical gremlins before, these two are less likely.
I really don’t know for sure, but I suspect that if the solenoid won’t release the lever, then it would have to be manually released by removing the centre console, and removing the solenoid. Alternatively, the selector cable could be removed at the transmission end, and the selector lever on the gearbox moved into Neutral by hand.
The solenoid is available as a separate part, at about £100 inc VAT, which isn’t the end of the world, but that isn’t much consolation at the moment.