Hi, Ant here from the UK. I love your videos.
I took a panel off in the passenger side foot well.
Once I finished, I forgot to stick it back on.
Two wires had dropped into the foot well, a black one and a red one. They were connected to something behind the panel.
I gave someone a lift, and they accidentally kicked the red one loose; it looks like it just needs to be plugged back in.
The air conditioning system no longer works, so it must be related.
How do I know where to plug it back in from inside the car?
Can you post images on the site?
How do I know where to plug it back in from inside the car?
easiest thing to do is probably assume the correct yoga position with a flashlight and look for the connector the wires pulled out of.
Can you post images on the site?
imgur.com
Please read the posting instructions.

How do I know where to plug it back in from inside the car?
How can we possibly know when you have not even identified what kind of car it is? It's pretty unlikely that anyone here is going to know where those wires go in any event. What you need is to obtain a wiring diagram.
Can you post images on the site?
That's covered in the topic "READ THIS FIRST - Forum Guide" posted near the top of the main page.