make sure vent has the correct sound device set, instead of lets say audio tech x34(which would be your sound card and depending on your headset would sound on your speakers and not the headset, maybe it should say Logitech V4E like mine which is the name of the headset. some headsets come with their own sound card and you have to figure out what the name is. maybe the cord is in the wrong place
if you have a green and pink cable make sure the colors match, if you have a usb, the above doesnt matter. make sure the installed drivers that came with the headset arent malfunctioning you can do this by going to control panel, system and device manager, could do it the techy way by going to mmc but. check to see if the driver has a yellow question mark on it. sometimes power surges during lighting storms can distort kernel environments in your computer, rarely but its possible, ive seen it done. check to see if the cable connections like where the cable ends and where your headset begins isnt lose, or the end where it goes into the mic and sound connection isnt lose either. unlikely but a likely cause. if you have a spare headset try it with that. i think its a vent setting with a wrong audio driver, it happens a couple a times. could try rebooting, once rebooted go into the sound taskbar on the lower right hand side left click and then find the sound properties and make sure the right audio device is selected then start vent and make sure the same and try it again.