What would be the sentenced jail time for a probation violation (failed drug test) if you had 15years probation, but you turned yourself in? And this would be in Fayette county, Ga.

It's all up to the Judge at your VOP hearing. You could get the original jail time. Go back and re=read your original sentencing paperwork. It should be spelled out in great detail there. The Judge does this as a sort of a reminder to himself should this person come before him again at a VOP hearing.