Hi Ethan,
It sounds to me like you have covered all the usual fixes i normally suggest and this fixes 90% of the problems.
I have a template I normally post with a list of fixes on it. I'll paste it for you below, even though it sounds like you have run through everything already. There may be something you have missed? So, apologies up front for repeat information!
Here goes:
WEBCAM BUTTONS
If you are using a laptop, does it have a webcam key you can press (usually on the one of the F Keys)? It normally has a picture on the F key that represents a webcam.
Normally pressing and holding the Fn button (function button) + the associated F Key will turn on / off your webcam when it is pressed. Sometimes you don't need to press the Fn key and just the F Key to cycle it On or Off.
Other computers can have a physical hardware button you need to press or slide into an On position.
Some laptops have a sliding lens cover that when closed or not fully opened properly will prevent your webcam from working.
If this does not work try the following:
PRIVACY SETTINGS
On your keyboard, can you press the Windows Key + I to open Settings.
Now click on Privacy.
On the left hand side under "App permissions", click on Camera.
First of all, make sure where it says "Camera access for this device is ON). If it says OFF, click the Change button and turn it ON.
Underneath this setting, make sure the slider under "Allow apps to access your camera" is turned ON.
Then under "Choose which Microsoft Store apps can access your camera" make sure the sliders for the Apps you want to use your camera are all turned ON.
Finally, make sure "Allow Desktop Apps to access your camera" is turned ON.
Close the settings and then try and use your camera again.
If this does not work try the following:
ANTI-VIRUS & FIREWALL
Can you also check your anti-virus software for any Privacy Protection settings it may have. Some anti-virus programs (like Kaspersky) block your webcam by default to stop unauthorised monitoring.
Also check your firewall software for Privacy Settings and also make sure that any Apps that want to use your camera are allowed to pass through your firewall.
If this does not work try the following:
UNINSTALL / REINSTALL
If you can Right Click your Start button and then choose Device Manager from the list.
In Device Manager, click the View menu and select "Show hidden devices"
Look for your webcam in the list. It might be under >Imaging Devices or >Other Devices. Click on the arrow > next to a category to expand that category until you find your webcam.
When you find your Webcam, Right Click on the webcam and choose "Uninstall Device"
Make sure you check the box to "Delete the driver software for this device".
Click the Uninstall button.
Now close down Device Manager and reboot your computer. Your computer will reinstall the webcam driver as it reboots.
When you have rebooted, check to see if your problem is resolved.
Let me know how you get on.