Can't turn face unlock back on, HTC one mini

[AC Question]

When I just had my phone, I used face unlock, to unlock it and a patern as backup.
Then I changed the backup patern and now i can't use face unlock anymore.
It's also not possible to turn de screenlock completely off. All I can do is chose between a patern, code or password. The other two option are greyish...
Please help me, I like the face unlock function

 

[B. Diddy]

Is your phone encrypted? Encryption limits your choices for unlock (although I don't think encryption allows you to use a pattern).

Go to Settings>Apps>All​, and look for Face Unlock. Is it Disabled? If so, tap it and tap Enable.

 

[Canastel2]

f you find you cant disable the lock screen or enable face lock in the security options because they are faded out, you need to "clear credentials" at the bottom of the security menu. This worked perfect for me