Hello. My name is Michel. I can help you with your question.
1.Turn OFF your device
2.Reset key depends on your device Brand(Samsung,Cherry Mobile etc.) For "iRola DX752"(Press and hold Volume +,Volume - and Power key buttons together
3.Wait for the "System Recovery Menu" to appear (Reboot System,Wipe data Reset, Apply update from ADB and Wipe cache partition)
4.Use the Volume keys(+,-) to select an option
5.Select "Wipe Data/Factory Reset" to reset your device(This will wipe everything on your device)
6.Wait for your device to be reset(the screen will display a spinning icon) 7.Select "Wipe Cache Option" 8.Select "Reboot System" to restart your device
9.Your device is now Reset
It should come up to the initial setup screens where you can go through the setup, set your account information ,etc. Once done, it will be usable again.