Hi skipjacks, thanks for responding. Nothing is pending with t-mobile, I was on prepaid account. I bought the phone like 10 days before leaving usa (due to emergency). T-mobile says my number on this new device should have being working for at least 45 days or so with refill balance. My cycle ended after 15 days of purchase and I really didnt see any reason to refill it as I was no more in usa. And no, I dont want to CHANGE my IMEI, only want to restore my own IMEI only. I am not sure if my EFS partition is corrupted, because I rooted my phone tried to backup EFS folder now (I know its too late but still), deleted it and rebooted (as a few threads suggested it would regenerate nv data files), but neither did I see any nv files when I did a back up now, nor after I rebooted. When I rebooted, the EFS folder did regenerate but there were no nv files in there. Also, after deleting EFS and regeneration the serial number was corrupted, but when I restored my backup, the serial number showed up correctly again. Also my current backup contains the imei folder with mps.code_bat file. I noticed that even imei folder was not regenerated on deletion of EFS and reboot. I somehow have the feeling that this is still indicating that my original EFS folder is still present (though I may be wrong, because I dont know). But my concern is the nv data files, which I dont see anywhere. I did come across several threads about imei corruption and restoration, but the only one I didnt come across was T-mobile SGH-M919 with stock android 4.3. I am wondering if this has some different file storage structure for imei (which again I dont know). At this point I am concerned about getting back my imei, I can get the unlock code from some reputed paid service again. I understand that open discussion about imei involving anything CHANGING IMEI is not allowed here. If anyone could just help me out restoring my original imei, even by pm, I would really appreciate it. I just dont want to throw away the phone and lose my money because of the error done by repair shop.
Second, since your IMEI has been deleted, you now have to change it, even if you just want to change it back to what it was before. The process to fix it now is what can't be discussed here.
IF you had backed up your EFS partition, then it would be as simple as restoring it in recovery. That's all well and good. But your IMEI is now 0, so you have to change it to what it was.
But all that aside, you went to a store and they broke it. Take it back there and raise holy hell until they fix it for you or buy you a new one. I know consumer protections are stronger in some countries than others, but wherever you are, yelling and screaming is a universal language.