The backward button doesn't seem to work suddenly

[AC Question]

All the sudden, it seems like my backward button is not functioning. I bring up the keyboard to type, but when I press the backward button, the keyboard doesn't minimize. It still stays on the screen. I have to press Home button to get out of that.

Is it something I can repair? Something that can be reset?

 

[B. Diddy]

Welcome to Android Central! Which phone? Does this persist after a reboot? Is it only when the keyboard is showing?