On my galaxy s7 edge after a reset
No read the sim card
Imei unknown
Regain your privacy! Adopt /e/ the unGoogled mobile OS and online services
To solve this kind of issue, I would flash the last version of the stock ROM (don’t do this if the last version is Pie or 10 since /e/ for S7 is on Nougat). Then flash TWRP and install /e/.
If I understood this posting correctly, carlopix uses a /e/ Phone with stable /e/ OS. Where can he download a new /e/ OS ROM?
I wonder why this error occurs now after a reset. So far everything worked fine.
@carlopix, what was changed on /e/OS before the reset occurred?
Yes i bought from e/shop. All it was working fine before reset i just wanted a clean os, but than not working the sim card and no imei… 
Any suggestion how to fix it?
Without flashing rom pls, i am not a modder 
Have you ever made a Nandroid system backup via TWRP Recovery and stored it externally, e.g. on microSD, since you first used your S7?
In this folders
[✓] Baseband
[✓ ] EFS
contains such important data as Baseband data and IMEI.number.
You did a factory data reset, right? S7: Settings > Backup & reset >> Reset Phone
No backup
Yes data reset
I have the imei on the box of the phone
Try this procedure first:
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Remove your SIM card from your S7.
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Restart a “Factory data reset” and set your date & language.
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Switch off the S7 completely once.
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Insert the SIM card and restart the S7 now.
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Check APN settings in your S7 under category “Wireless and Networks” you will find the item “Mobile Networks”.
Sorry i try but not working
Can you boot into TWRP Recovery?
TWRP Recovery :
With the device powered off,
hold Volume Up + Home + Power.
When the blue text appears, release the buttons.
Yes than what do on it?
For example, to install a flashable-baseband.zip.
“Without flashing” (installation) a repair will hardly be possible. You don’t have to be a “modder” for this simple activity.
What operating system does your host machine use?
Yes it works i flash lineage os and the imei is back and all it works fine.
I will try to put e/ back into it 
Many thanks again i flash a phone for the first time