This is probably the most effective way to get IMEI back without losing any data, etc.
Let's start now....
1. At first download Root Explorer from Play Store and this zip files (Link- http://www.mediafire.com/download/o7nhe51zd18nj3l/IMEI+Corrupt+fix+CWM+flashable+ZIP+%28IMEI+corrupt+by+flashing+WRONG+recovery.zip)
2. Now open Root explorer goto data and you find a folder name 'NVRAM' copy it to your memory card..
3. Now the other zip file you downloaded, extract it (By 7zip-PC) (By MiFileExplorer/ES File/any thing else-Android)
4. Now delete the NVRAM folder from the extracted zip file (data>NVRAM)
5. Now copy the NVRAM folder which you copied earlier by Root Explorer and paste it on the extracted zip file (data>NVRAM)
6. Now rezip the extracted files & flash it through Philz recovery without wiping anything... You will get your IMEI back, 100% working worked for me too....
Credits
1. Arnav for the zip files
2. Zia Bablu for helping
3. Snigdho Hasan (Me) for writing it :P
