No sound out of headphones.

Hello,

I like to change between playing sound without my headphones and with them a lot, depending on whether or not the people in my house are sleeping, and it usually works just fine.
But today, when I plugged my headphones back into my tower's headphone jack, there was no sound.
I've tried everything.
My Headphones are set as the Default Device.
I've reinstalled my sound drivers.
I've looked on Google,
and of course, lots of restarts. But nothing. No sound.
The headphones do work, by the way. I've tested them on my laptop.

If it's any help, my computer is a tower only, connected to a TV which I use as the monitor through HDMI.
Thanks for the help :)