Auto-lock never missing in IOS 9.2.1 Surprised I could not find this asked. 

Is there a way to get Auto-Lock "Never" option back in IOS 9.2.1
Actually i also experienced this. I got this solved because I read a thread regarding this. It's happening because we install some certificate to our iPhone. For me I installed google something management certificate in order to use the google sheets. You can remove it by go to General>Profile.

Hope this can help you.