CPU’s front 3.5mm Headphone Jack not Working

I assembled a new PC with the Motherboard being of Gigabyte. The CPU has 3.5mm headphone jack in its front as well as at its back. I usually watch movies in my PC and if I plug the headphones at rear side the wire is short to reach my ears. So when I plug it in the front 3.5mm port there is no sound coming from it. It even doesn't recognise the dvice. I have checked the cables. All are attached fine. Front USB ports are working but headphone port is not. Please help.
