Alright, following a Microsoft support tutorial, I used the "Add Legacy Hardware" command to reinstall my computer's original Realtek 2013 Audio Driver. No such luck, but at least the computer had an audio driver. I then noticed a warning on the driver, went into properties, and found out that the driver simply wasn't on (Code 10). I searched for other drivers with the issue, and found under the "System Devices" tab that there were two "High Definition Audio Bus" that had errors, a "Code 19: Corrupted Files." I uninstalled the two buses and uninstalled the 2013 Audio Driver and rebooted. After the reboot, there still was no sound, but two "High Definition Audio Controller" were installed, as well as a 2016 Realtek Driver. A little bit of patience, and voilá! my headphones began outputting sound again. I don't know what the issue was, or why the AMD Graphics Driver caused it, but I'm glad to finally have my sound back.
P.S. My computer didn't even have a RTKVHD64.sys file whatsoever. Installing a new one didn't fix the issue, and I don't know what it is or why it was missing.
P.P.S. Thank you so much for all of your help! As I said previously, I've gotten more help from you than all other support tickets combined! I'm a huge fan of Paradox Interactive's grand strategy games, and look forward to the release of Crusader Kings III.
Farewell, and once again, thank you