Carp can you hear or speak in team speak? If you can I would guess some how your audio got turned off in the game. I am not a computer nut so this is just a guess on my part............STRYKER.
If somehow you graphic card as autoupdate on, maybe it activate the monitor speakers (if you have), if your using usb dongle to headset, unplug and plug again
I loss sound while playing sometimes when someone in the house walks by my room quickly. Static charge will shut mine down. I have to reboot then. Try changing USB ports to get sound back if that fails.
PMG Carp.. You are not the only one with problem issues. I just got a new headset and after installing it on Wednesday it was great no issues. Then the following day "BOOM" they could not hear me in voip and TS was okay. So what I did I rebooted the PC and after I rebooted there was an update to me Nvida cards. I then could talk in voip which is squad yay!