Stop using turns, disband your fleet. If you are terran put all the land on your colonies into commercial. Now use one turn. If you are making more than your debt interest, continue using turns until you are out of debt.
If you are still making less than debt interest go to the market and sell everything you have. If this does not bring you out of debt or make your income higher than your debt interest ask people to use artifacts on you that give you money. If all else fails restart.
good luck