do NOT spend turns
go to manage fleet
disband all ships
(ships cost money per turn, called "upkeep")
click on income, if income is positive then spend turns, reaserch and build commerical etc.
if not, sell all your minerals ore and stuff (keep enough food for yourself though)
and then check to see what your income is again
if your debt interest is still higher than your income, then you have to start over
you restart by going to "options" then clicking "restart empire"