Passenger door no longer closes

Hello guys, I’m new here in the forum, driving a cherry red B4. Have so my problems with it, therefore this search for help. The most current problem is that my passenger door does not remain honorable. Whether I lock it or not has 0 influence on it.(That means at the moment I have tied it to the handbrake with the belt, which is of course not a solution. I have a door panel for you, but then it stops. Maybe someone can tell me what exactly I have to look for in the lock. Wär Lieb