spacebar not functioning

That's interesting. 

Here are my guesses, in the order I'd eliminate them in:

• Does your space bar work in other applications and/or in the browser?
  • I'm assuming you posted this with your browser, so I'm guessing yes, but it's worth asking.
• Have you rebooted the computer since you started experiencing this problem?
  • Do an actual shut down, let it sit for a minute, and fire it back up.
  • This probably won't fix it, but it eliminates a lot of weird possibilities that might otherwise be in play.
• Is this all Flash content, or just a specific website or game?
• Are you using an IME or multiple keyboard layouts?
  • Depending on how the Flash content is written, they may be looking for a specific key code.  I'm not sure why the spacebar value would have changed, but it's possible.  It's not my area of expertise, but there are still a surprising amount of changes in the ecosystem around internationalized text.  I don't track it super closely, but it wouldn't surprise me if a browser rolled out a new feature that's correct, but breaks assumptions made in old Flash content.
  • In that instance, I'd be curious to know if switching to an en_US keyboard layout "fixes" it.  If so, that's what's going on.
  • If that's the case, you may also find that it happens in some browsers but not others.

If none of that helps, some details would be useful:

https://forums.adobe.com/thread/1195540