First of all, can you hear anything when vent is not on?
If not then you need to check if you accidentally muted your sound on the headset or PC. If you haven't then hold down the windows key and then the R key, in the box type services.msc, then hit enter. This should load the service window. Find windows audio, right click then choose restart. See if this fixes the problem.
If you can hear with vent off, then you have a conflicting sound data coming from some where, switch off all your applications and check if it fixes the problem by just loading vent.