I suppose you have a non-European nationality, correct?
I think you have already lost your Niederlassungserlaubnis, because you moved out of Germany for more than 6 months.
(§ 51 Abs. 1 Nr. 6,7)
Therefore it is not possible to obtain German nationality at the moment.
In former times you should have applied for the EG-Daueraufenthalt.
You should try to obtain the French equivalent, based on Article 2b of EU-Directive 2003/109/EG
Actually I am in serious doubt whether you are allowed to stay in France without having the mentioned EU-Title. How did you get a working permit in France?
Please check your existing Aufenthaltstitel in your passport!