I've been having this issue the past week or so with my H61 mobo audio. The drivers etc are apparently installed but after a reboot I lose all audio. There is no icon etc in the tray. I did manage to get it working by doing a system restore to a point where there was no security update from microsoft essentials (I think this is the culprit) but now to no avail I'm not sure what to do! Am currently trying to uninstall the drivers and via device manager (even the hidden ones) and rebooting hoping that will help.

Has anyone has this issue? It's driving me round the bend