I was driving my 2009 Toyota Corolla Ce on the highway today when my check engine light began flashing. So I got it towed back to my house for my grandpa to take a look at. He used a code reader to confirm a misfire in cylinder 1. Upon removing the spark plug we discovered the 'arm'/ piece guiding the spark somehow came off. We used a camera into the cylinder but could not see it on the screen how concerned should I be and can I plug new plugs in and just go again?
Without a picture of your spark plug it's impossible to say whether the electrode broke off, or whether it's eroded to the point it could no longer make a spark. I'm going to assume that the electrode is missing, not eroded. If it's eroded and it's really old then replace all 4 plus, if it's new and eroded you may have a problem, but that's a separate question.
It's right to be concerned, you shouldn't try and run the engine until you make sure the electrode still isn't in the cylinder, or that you don't have cylinder damage. The electrode could have rattled around and scratched up the cylinder walls, or become embedded in the piston. It sounds like you've already had a look, but have a more thorough one and with the piston at the bottom of the cylinder and look for scoring. Use a magnetic pick-up tool in the cylinder to see if you can get out any other debris.
If the electrode isn't in the cylinder it's most likely been blown out of the cylinder's exhaust valve, in which case it's likely been lodged in your catalytic converter. If that's the case and you can't see any cylinder damage then you're probably good to go, replace the plug and move on unless you are willing to pay for a partial teardown of the engine.