I don't know if your device is rooted. You must first root your device using either framaroot, kingroot, iroot or any other root application.
After root or su permission is given to your phone, you can use any root browser and navigate to /data/nvram/MD/nvram/NVD_IMEI to change the MPOB,001 file.
Alternatively, you can just use SN Write tool to write IMEI to your phone when baseband is already available; check baseband from the directory: system/about phone/baseband version.
Alternatively, you can use an imei tweak apk like chemelephon from play store and write imei to your phone and after restart, your sim will be detected.
But baseband should be available before you can use alternative 2 and 3 so make sure to check baseband first and su permission as well.
But if baseband is unknown, you can try and use miracle box to fix unknown baseband. This approach is su or root independent.
Very relevant applicantions for android phones.