2009 ford fusion saying I have 0 miles to empty?

I was running low on gas the other day so I went and bought a gallon. The electronic milage counter said I had 30 miles left which was about right. Then I drive a lot the next day so I put another gallon in there from a gas can. The milage dial that reads E to F went up (if that makes since) but the electronic counter did not increase. Now the dial days I have about a 5th of a tank but the electronic counter says I have 0 miles to empty. What's up with this? How much would it cost to have this fixed?

It will cost you the price of a tank of fuel to fix.

You didn't add enough fuel to reset the range counter. Many cars will skip from around 30 miles range remaining to 0 miles remaining because they can't/won't calculate range any closer than that to empty, and that's what yours did. You need to add more than 1 gallon of fuel to allow the range computer to reset itself. When you fill it up full again, it should reset by itself without you having to fix anything.

If you have that little gas in the tank it is bad for the fuel pump.
try filling the tank and see if that helps.

Search YouTube or Google on how to re calibrate the instuent cluster once in a while my Chrysler voyager needs the cluster recalibrated an it fixes problems with the gauges every time.