invalid argument

my samsung Grand 2 SM-G7102 shows SAMSUNG LOGO ONLY and while going to recovery booting option it shows E:failed to mount/system (Invalid argument) :crying::crying:

HALP! failed to mount /data (invalid argument)

I have been trying to reinstall the stock ROM for my BLU Energy X Plus, after trying a few custom ROMs I found.
After trying SP Flash Tools (doesn't find my phone/preloader even with the VCOM drivers installed), I decided to risk playing with fastboot. Boy, am I sorry! I managed to get TWRP back as my recovery, but now /data will not mount. When I try to reformat, I get an error saying it needs a partition size. I think I really f'ed up my partition table somehow :(

pls can anyone help?

Need Help on Sph-720T! - Failed to mount /efs (Invalide argument)

When I flash stock roms using Odin, it works fine.
when I flash twrp and then go in to recovery mode, I hit clear cache davik, i get an error "Failed to mount /efs (Invalide argument)"

I never got that error before, that error appears when flashing custom roms too
Now when I load custom roms that worked before, they are getting stuck at the initial loading screen.

I search and searched the web, didnt find anything on my phones model but instructions on other phones to use ADB command line while the phones in recovery mode with system mounted
I tried everything I could find to put in the command prompt, 4+ hours of searching and I've come up bare.

If anyone could help me I would appreciate it, I just want to be able to flash custom roms with no issues.