Actuators. They're 2 small pot-metal parts inside the column head that join the lock cylinder (key) to the ignition switch (wires), and they're notorious for breaking. They're even more notorious for being PsITA to replace, so call around to your local indpendent shops & used car lots for the name/number of a mobile steering column specialist who will rebuild yours for ~$100. That's about what a working used column would cost (before installation), and you wouldn't know how long it would last before you'd be right back here. The actuators are available online, from Ford, and at many parts stores for $15-50.
Until then, remove the plastic column shrouds between the wheel & dash, and push the operating rod forward for start/run, and back for off/lock/accy.