unlock ZTE Avail Z990 hard reset:

Turn off ZTE Avail Z990. Just hold the volume up key + power button + the options button (3 lines button on the bottom left) all together then the android screen will come on and select the master reset wipe all data. (you select with the back arrow button on the bottom right) and then scroll down to YES delete with the back arrown button again and then reboot phone and ur done! All data will be lost! Back up your data before doing hard reset!

or hold volume up+power+option you will get the android screen drag down to reset using down vol key
confirm with rotation key

ZTE Avail hard reset

Reset through menu Privacy: Reset to Factory Settings

Press the Menu Key or enter menu > Settings > Privacy > Factory data reset > Reset phone > Erase everything.
WARNING: All your personal information and downloaded applications on your phone will be erased
after resetting the phone.

Here are the steps for doing a master reset using the hardware buttons for the AT&T Avail

• Remove memory card
• Emergency Calls
• *983*987#
• Dial

General advice: Before you buy a new cell phone or new tablet, please try the following procedure to repair your device. First charge your battery, backup your important data if possible and in most cases take out SIM and SD card before factory reset. It is impossible to recover your data after doing a hard reset, so online backup is always important. For all of your data, a backup should be done on an external device, hard drive, raid system or media. With or without insurance, if your cell phone lost, damaged or stolen at least your invaluable data is backed up in a safe place. If you are about to sell your phone and you want to wipe your personal data, or if your phone affected with virus you have to do a hard reset. In some cases, you can delete the forgotten password or lock pattern from your device as well. All information is for devices with stock based ROMs. If you are using rooted device, always back up your EFS folder first, containing your IMEI info, etc.!