During Android Encryption, I lost my device keyboard and OS ask me to enter password?
First, have a look at the answers to this question.

If none if them works for you and you have access to the recovery, I think you can only wipe data / factory reset your device.

If you don't have access to the recovery, you can still factory reset the device via fastboot with fastboot erase userdata.

Factory resetting your device will delete your data though.