NEED HELP ASAP, Audio Dispeared

Hello, 
I am in desperate need of help. My audio is completely gone, doesn’t show up in device manager, services, or settings, its like it was completely wiped from my computers drive. This is the second time this has happened and I cant afford to send it off for troubleshooting because I am in a middle of a class and need audio in order to take my online tests. I am going to have to use my brothers microphone for now, but for some reason even though I am connecting audio to my computer through pairing it wont let me use them when i go into my test. I have tried as much as I know how and even used AI to try and help me. Is there an audio file or something that I can just download?