In a short research I was able to find out that an entry and residence ban (Wiedereinreisesperre) usually does not last longer than five years ( § 11 Residence Act (AufenthG)). The residence ban is usually one year when it is issued for the first time.
Further information on the residence ban can be found here:
The entry and residence ban can be lifted or the time limit can be shortened.
In the event of unauthorized entry, you can be turned back at the border (refoulement; §§ 14, 15 AufenthG).
However, I read from your last question that your case is more complicated than that and that you have already contacted Sweden, Greece and German authorities as well as Proasyl and other help organizations. In order not to discuss your concern in two questions at the same time I would say that we are in this question:
I hope you are well.
With kind regards