I will pay attention to ZP980+ phone, but this procedure can be applied also to other phones with MTK chipsets.
So first of all it is backup your IMEI from your phone. Of course your phone have to be fully working.
NOTE: do ALL this stuff at your own risk. Before doing this, you should probably backup your phone.
- download and instal MtkDroidTools on your computer.
- run it and then connect your phone
- click on ROOT button in program window
- the backup will be created on "BackupNVRAM" subfolder in "MtkDroidTools" folder.
- you can also restore your backed up IMEI, clicking on Restore button.
You need a rooted phone and installed some root explorer on your phone for this method.
- go to: "data/nvram/md/NVRAM/NVD_IMEI" folder
- copy all files from this folder somewhere on your computer
- save this 3 files on safe place you will need it later for restore.
- for restore lost IMEI download this file: http://d-h.st/4ana
- click on it with right button of mouse and choose open with WinRAR
- clicking on the folders to get the "NVD_IMEI" folder
- find your previously backed up files on your computer(MP0B_001, ST6TA001, ST6TB001). click on your IMEI files and drag and drop it to inside this folder
- close the WinRAR and then put the imei_restore.zip file to the phone's memory or SD card
- flash this file via recovery and reboot your phone.
this is collected and rewrited guide from different sources on internet. thanks to xdaforum users, also thanks to user with nick smokerman.