My aparment was a studio with two windows and was renovated and a new room was added. One window became the passage to the new room and the other window became an open space. I moved back into the apartment and requested the LL to close the window space and put a door on the passage but he says that it will done after inspection. He is already charging me rent for a one bedroom apartment. Can he charge me without having finished the renovations? We don't know what does inspection has to do with this. Is he trying to get away with something?
It sounds to me like your LL doesn't have a Certificate of Occupancy yet and is waiting until an inspector decides the work is up to code before he makes what could be illegal changes.
If there isn't a window in each room, filling up the window space and installing a door may be illegal.