Golf 4 (2000) Tailgate Lock Issue: Key Doesn't Fit - Lock Replacement or Alternative Solution?

Hello, I have a problem with the tailgate of the trunk in Golf 4 2000r the problem is that the key in the lock does not go at all, it is a problem related to the fact that the key (I have one) is different to the trunk lock than to the door and the ignition? Can I help him somehow or do I need a new lock with the key? Best regards and thank you in advance for your help

If you have a central one, it is very likely that the lock has found, it is worth trying to treat it for several days with a penetrating fluid.

I forgot to add that I do not have a central lock

After inserting the key in the flap lock does it move gently?

It is possible that someone was exchanging the hatch, lock or door locks together with the ignition.
Just remove the handle and take it with the key to the key holder. This one will fix the insert in the door handle or rework it for the key you give him.

I did this to myself, WD40 into a lock, and I heated the key tip with a lighter, and then rummaged in the lock with such a heated key.
As in winter, when the lock freezes from water in it, and I write only about the insert, with something with which you put the key.
You will not heat the lock itself without removing it, also with the key. Wic is to warm the tip so that it does not melt from the plastic key holder. So you need to feel sensitively, not the redness of the metal and the plastic flow, a little while you can still grab the arrowhead and not burn yourself with 60C.
It helped with rusty lock inserts, it was possible to insert the key in installments and start turning it. Fun time from 5 minutes to an hour.
Further finding the lock behind the insert, on the strands, plates in the lock or whatever is there, it's probably just dismantling the lock and its rust removal. And here can be a problem, because you need to remove the lock from the closed flap? I don't know how intelligent you need to be to replace a lock or flap without a matching key. Have you bought this car now or not, and the lock has stopped working over time? Can you open the flap to remove the lock mechanism?