Can not boot, mount, wipe, change file systems on android I had a Samsung Galaxy S Duos 2 with stock rom so i decided to flash a custom rom 7.1 Nougat by developer ishant (he has done a nice work).

I flashed it and it worked fine, but since it had some bugs like (dual sim not working and after logged out from Play Store, could not log back in because Play Store keep'd crashing). I decided to reinstall stock rom 4.4.x . But could not do that because i can not wipe, install, format, change file system or mount anything.

Every time i wanna try an option in TWRP Recovery its keep saying: 

Unable to mount /system
Unable to mount /data
Unable to mount /cache
Unable to mount /efs
Unable to mount /preload.

Of course it does not boot.

On Wipe -> (select anyone of: System, Data ect) -> Repair or Change File System. It does nothing and every of this options shows: Present: No, Size: 0MB, Free: 0MB, Used: 0MB, Backup Size: 0MB.

I am able to connect via adb.

Any idea is appreciated.

Thank you
Just flash the official ROM or the appropriate PIT file and custom recovery via Odin, then try booting the phone. It will work.