LUCK I HOPE
I know very often a reply can sound patronising, but this is not.
If just one of the buttons has become 'stuck' then none are likely to respond.
From the picture (and I cannot see all the buttons) it looks as if the 'Enter' button is depressed..
As I said, if just one button is stuck then none of them will operate.
It is not so much a matter of how far the radio dropped, really how lucky you might be.
You can use a tool to help 'wiggle' the Enter button and see if it pops back out, if your finger cannot do it, but obviously be careful not to cause damage.
Your fingernail might do it. A flat jeweller's screwdriver gently pushed into the spaces around the button might also do the trick, just to help move the button a bit to the left, right, up or down.
You must, and should not need to use force, just very gentle movement. It is not only the button you need to be careful about, but damaging the plastic around it.
Something like a plastic or wooden toothpick would probably be better. Also very gently trying to lever the button back in place may do the trick, but that needs to be done with the utmost care.
At least you will know very quickly if you have succeeded.
If the button does not pop out on its own, then someone will have to physically get to the keypad and examine it for damage.
As none of the plastic case appears to be cracked or broken it is unlikely you will have bent any of the metal behind it, which is good news at least.
Apologies if my replies are totally unprofessional and amateur, as some might firmly believe, or at least one person I can think of, lol.