If you encountered such Problem, This Method might Work For You as it Worked For Me.
Follow The Below Method and You Are On Your Way To Unlocking Any Modem!!!
Download and Install Dc-Unlocker Software From HERE
After Installing It, Plug your Modem with any othe network's Sim card. (if its Etisalat Modem, Put Mtn or Airtel Sim in It).
Close the Modem Interface that will show Up, Then Launch Your DC-Unlocker Software that you Installed in Step 1.
Select The Manufacturer of your Modem; Mine was Etisalat ZTE MF631 so I selected ZTE from the Manufacturer List
Select "Auto Detect" from the Model List So It will automatically Detect your Modem Model.
Click on the magnifying glass icon to allow the program detect your device.
After It Might have detected Your Modem Model, Click on "Unlocking" at the Right hand side of the Screen, You Will see an Option To Unlock. Click on Unlock and you Will see a Message That Reads: "Modem Successfully Unlocked"
Close the Software, And Start Enjoying Your Modem with Any Simcard of your Choice!!!