I have successfully reinstalled a keyboard driver after having an issue (NumLock acts as Volume up -- nothing too bad -- but SPACEBAR acts as volume down!). Without having to resort to disabling fast startup (maybe a better solution than installing an older version of BOOTMGR, really, to avoid the OS Choice graphical screen, which is the cause) how can I fix this? A smaller, nonimportant thing, is starting an autohotkey script in all sessions (it's compiled, it changes a few shortcut keys on the session, namely two keys that I don't use and now could use as actual volume keys -- I don't have media buttons)
It looks like it is a Function Key. F1, F2 and other Functions keys allow you to adjust monitor brightness, volume and such.
You can use FN for the moment. Functions Keys are deep in the BIOS but could be re-mapped by most programs. Re-installing the keyboard would be the best way to solve the problem.
As for the Hotkey Script, it's because you added it as a startup item in the Boot Manager. You can ask it through Task Manager.
I would suggest not use Hotkey Scripts to remap. It's recommended in the Help Pages. You should use AutoHotkey to create Hotkeys solely or for automation.
Remapping keys with autohotkey is a common error.