the starter is a relatively simply circuit. the case is typically ground, there is a b+ constant post, and there is a small wire to actuate the solenoid. if you have b+ while cranking at the post, and b+ at the solenoid wire, you must have a starter issue. i used to start my car with a wire all the time when my ign cylinder went bad. just jumped a wire to the start signal on the solenoid.
if you tried everything, then it could be a problem with the starter.

__________________
-Alex
'10 Ranger XL 2.3L Manual
Mods: Stereo, Tint, Weatherguard rain shields, Intake silencer removal, LED brake, turn signal, reverse, license plate, and dome lights, DDM HID's (currently removed), lowered, 17" wheels with spacers, Explorer autodim mirror with Autolamps, Magnaflow exhaust, Buggman LED 3rd Brake Light...