Hello,
It's an easy fix, when it comes to the keys. If the key is stuck, you can apply pressure to the button and it will return back to normal. But, if the key is broken then you can easily use a tool that has a a flat tip and go underneath the key and pop it out. The key will then come off and you can easily replace it with the new one. It's quite simple, you can just place the key in the empty spot and push it down and it should easily fall into place.