I deleted my IMEI number when flashing roms a few days ago and it was showing as 000000...
I searched everywhere for a recipe of how to restore it and could not find one that would work. The closest that I got was a brilliant post (see link below) describing how to restore the IMEI on a SGS2 i9100. After following this recipe, I was able to restore my IMEI number to 0049 .... which is just as useless as 0000....
It took me a couple of days of research (and HUGE thanks to everybody whose previous research I was able to use) and I finally succeeded in restoring my IMEI using the 9 step process that I describe below. I can't guarantee that it will work and I do not know if it will work on any device besides the SGS3 GT-i9300 (international SGS3), because this is the only device that I have and was able to test the process on.
Restore IMEI on SGS2: http://forum.xda-developers.com/show....php?t=1264021
Download EFS PRO: http://forum.xda-developers.com/show....php?t=1308546
Download your original firmware using check fus downloader (http://forum.xda-developers.com/show...032437&page=18
-EFS PRO, a brilliant little program for Windows used to backup / restore the efs folder as well as recover / repair the nv_data*.bin files.
-Windows USB drivers
-Original phone firmware (actually, you only need the modem.bin file, so once you download your firmware package, you can just extract the modem.bin file).
-Odin or Heimdall
Your phone's IMEI number is stored in the ".nv_data" file in the original shipped efs folder.
1. make a copy of your EFS folder using root explorer and store it somewhere safe (on your SD card and external SD card should do it).
2. delete the EFS folder from the root of your phone using root explorer.
3. reboot the phone
4. open root explorer and go to the EFS folder (yes, it is still there! The Android OS has generated a new one for us) and delete the following files:
and the entire IMEI folder.
5.Now go to your backed up EFS folder on your sd card and copy the IMEI folder and the " .nv_data" file (note the dot) to your new EFS folder.
6.Make another copy of the ".nv_data" file in your new EFS folder. Rename one of them to "nv_data.bin" and the other one to "nv_data.bin.bak".
7. Connect your phone to your PC and start up EFS PRO. After your phone has been detected, press the "Repair nv data" button to correct the ownership and permissions.
8. Reboot your phone into recovery mode using the three botton combo and flash the original modem firmware (the modem.bin file that you extracted earlier) to your phone using Odin (use the "phone" button for the upload) or Heimdall (use the "radio" partition for the modem.bin file upload).
9. Reboot the phone normally and your IMEI number will be restored and you will be able to connect to your mobile network again
Good luck and let me know how it goes