"although I have not done an Envizen tablet most android tablets are the same in there hard resets . first check to see if there happens to be a reset button anywhere on the tablet .
If not,First, turn your tablet off. Then, power the tablet back up by holding down the volume (either + or - ) and power buttons simultaneously. Continue holding the volume button until the screen says ""Booting tablet in recovery mode."" This will give you a picture of an Android. Tap the android, and you will be given a screen with several options. Move between the options with the + and -, and select with the power button. Go to the option for Factory Data Reset and select it. Scroll down to `the Yes, and then the tablet will erase its memory back to factory settings. Once it has completed, select Reboot Tablet Normally. Remember when you do a factory reset you lose all data and it will be like the day you started it for the first time all apps photos, music, addresses and phone numbers will be gone so back that up before you do this . Hope this helps"
