dismantle a single key from keyboard

At first I thought the backspace-key is dead, but infact you have hardly press it.
You hear the click every time you press - but that doesn't mean it will be active.
Does someone ever had a problem with a single key? Any suggestion how to improve this?
Due to the small keyboard I need this key even more than usually

 

I get this problem all the time. Usually there is something stuck under it. All you have to do is get your finger under the top of the key, pressing down on the ins and del keys, and pop it up. Kind of like hinging it on the bottom edge. To get it back on, just slide it in from the top, and press down until it clicks.