How to unlock my HTC desire 816 w after too many pattern attempts? I got my phone locked after too many pattern attempts. Now it is asking me to enter my Gmail credentials. I tried that too but nothing is happening.

I have active data service but it is not enabled in my phone.

I tried to hard reset my phone, but when I tried to enter into Recovery mode by pressing Power button + volume down key, nothing happened.  Fastboot is enabled.

How can I unlock or reset my phone?
It depends on which OS you are using.  It is my understanding that phones with newer OS cannot be unlocked/reset if the device password is not known.

This is an attempt to make it more difficult for people to reset stolen phones.

Bottom line, depending on your specific device OS - you may need the password to unlock it.