Try different guitar cable, check if jack socket in your guitar is firmly secured, then experiment with your position during recording. Turning around or walking away of your amp you could find quiet spot. Change AC outlet you are using, turn off computer, and everything else. Truth is, there is no easy answer when it comes to a buzz, I've heard about a studio where they had to plug a fan into the same power strip as guitar amp to get perfectly quiet recording. The fan was not working it was only plugged in. Nobody knew why, they discovered it by accident.