Fixing instrument cable? (I think)

Well I go to plug in my amp a few hours after it was working just fine. And the amp turns on but it doesn't amplify any sounds. The only way it amplifies the sounds of my guitar is if I apply tension to the instrument cable connected to both the guitar and amplifier by pulling the cable or squeezing it. So I think the problem is the cable. Does anybody know how to fix it? Any help would be greatly appreciated.

first, check the wire is properly connected to the jack. unscrew the casing around the socket, and see if it's properly and securely connected. if not, you need to re-solder the wire to the plug.

this video shows you how: click