In case your IMEI number gets changed or you get an error saying Invalid IMEI number, there is no need to panic, you can easily get your IMEI number back. This is an error that rarely happens when installing a customized ROM. Before you begin you need to note down the IMEI number. There will be 2 IMEI number in case of a Dual Sim handset. You can find the IMEI number on the box pack and/or mentioned in the Battery Compartment.
This may or may not work on your handset, but worth trying. Open the Dialer and type *#*#3646633#*#* you will enter the engineering mode.
Then swipe left to connectivity. In connectivity click the CDS information option and tap radio information and then tap phone 1.
Now enter the command
AT+EGMR=1,7,THE-FIRST-IMEI-NUMBER
And press enter.
For second SIM tap phone 2 and type this command
AT+EGMR=1,10,THE-SECOND-IMEI-NUMBER
And press enter.
If *#*#3646633#*#* does not work and if you are using a MediaTek powered handset you can download the utility called MTK Engineering Mode for free from Google Play, it will do the same.
