Samsung Galaxy S7's IMEI gone after flashing another ROM

[ABDOLMALEK1234]

Hi
it would be very appreciate if you help me
when i tried to flash a ROM via recovery
i have no IMEI
i tried and tried and i had same result : NO IMEI
i tried to download original ROM from sammobile and no IMEI
PLS PLS PLS PLS help me
Also i tried and tried repair imei through Z3X tool and nothing happened
i didn't backup efs i don't know this will happen
my android verision is 6.0 marshmallow
i tried upgrading it to nougat i did the same thing and nothing happen
i downgraded to 6.0 and waiting for fix

 

[njdan30]

Do you have efs backed up? You can use a tool to write imei- esn number but you need your 6 digit msl and Samsung 16 digit password, the password is easy to obtain Its posted on xda and you can Google it

 

[ABDOLMALEK1234]

what is the tool ? Z3X? Octoplus? octopus?