If you've checked the fuses, then:
If it ends up being a bulb, see sources and related links below.
Check your fuses.
Most likely the resistor has gone out! Check the fuses; undersize fuses will not work!
Try checking the turn signal flasher. Not to be confused with the hazard flasher.
Assuming that the Fuses and Flasher underneath the dash (Driver side fuse panel) have been replaced. Check the Fuse Box under the hood adjacent to the Battery along-side the upper fender wall. The MAIN fuse may have blown, disrupting the entire positive feed.
Did U checked the turn ligths flasher, switch and wiring?
If both sides are out as well as the hazard lights then the flasher relay is suspect.
Turn signals
first check your coolant level. then check to see if you have a leak, then check to see if you cooling fans are coming on then check if your thermostat is working.
by the fuses
Turn on the radio and start pulling fuses. When the radio stops working, that is the fuse. Try the cigarette lighter fuse first.
According to my 2001 Sport Trac Manual Fuses 4,5,23 @ 32 are not used for anything.
Check bulbs Check the relay in power distribution block Check the operation of the switch in turn signal stalk