How to get disappeared keyboard back? I am using Android 5 and, on rare occasions, my keyboard disappears or becomes unavailable when I enter editable fields in different apps (browser, FB, etc).  Once that happens, what can I do, other than rebooting, to get the keyboard to reappear once I am in editable fields?
I have seen this on rare occasion. Often simply backing out of the app, and optionally removing it from the list of recently-used apps (which quits an app a bit more calmly than an End/End All), will restore functionality once the app is relaunched.

Sometimes a web page or web-based app, like Facebook, will refresh itself in the background, and that can disconnect the keyboard from the field being edited. Sometimes it's a slowdown elsewhere in the phone.