Additional information about your setup
What is the problem?
Camera not outputting anything
What did you already try to solve it?
Restarted Octoprint and did dmesg to look at errors.
/var/log/webcamd.log, syslog, dmesg, ...)
(OctoPrint version, OctoPi version, ...)
Did you turn on your printer before starting the pi?
We had cases where the camera didn't work properly when the printer was powered by the pi.
You can rule this scenario out by disconnecting every usb device but the camera from the pi before powering it up.
I restarted the pi (for good measures) and only had the camera plugged in and still did not work.
I restarted again and fixed the webcam issue. I don't know what happened but it fixed the second time around. Thanks for replying and trying to help!