If that didn't work, you may want to try starting up the device in "Safe Mode" and see if it shows up then. You wouldn't be able to run most apps in "Safe Mode", but you can try some things that use the keyboard. If it does work, then you have something on the device that is causing the restriction. An app, malware, virus, etc. If that is the case, you will need to remove whatever is the cause and then restart the device after it is gone.
To get into "Safe Mode" please do the following.
1. First turn off the phone.
2. Next press and hold "Power" until you see the manufacturers logo on the screen, then release the power button.
3. "Quickly" press "Volume Down" and hold it for few seconds until you see the message "Safe mode: ON" or...