Unable to unlock my phone after completing the Android 6.0 Upgrade

[AC Question]

Hi, I am using Lenovo K3 Note phone and I was able to complete the Android 6.0 upgrade without any issue. I did try power off and restart my phone as the contacts were not displaying on the phone after the upgrade. But for my bad luck, I am unable to unlock my phone even after giving the right pattern lock code.
Please help me to resolve this issue.