Picking daisies to fix Taurus windows.
You can't know all have failed--and it would be a very unlikely event unless all were overloaded at the same time, both up and down.
You only know that the driver window switch Up function (or was it Down...doesn't really matter) is lost, indicating almost to a certainty that driver's window switch has "half failed" - which is really no different than "all failed. So you want to change out the driver's switch. But from where? The parts department or store?
The good news is that you will probably not have to buy 4 switches; or three; or two; or, perhaps, even one.
Let's assume only the driver switch is defective...because switch fail in one direction only indicates a switch failure in this case (had relay froze or breaker broke, then no UP or Down by any window. The question now is where to get a known good switch. Actually you have as many as 3 "suspected good" switches. So pulling one or all of those will provide a "stock" of "test" switches to try as the driver switch replacement. But let's be lazy and try to pull as few switches as possible.
Factor one: let us assume, for example, that the rear switches are the least used (depends on children or dog kids, and how they are harnessed, or not, I would suppose; so you could pick the passenger switch if you like - the idea being to use the "least-used-previously" switch...because you want the "new"/test driver switch (and circuit) to be the most reliable, and it would seem safe to say that the second most used switch (typically the front passenger switch) is closer to failure, whenever that might come to pass: could be minutes, could be many minutes.
Now, is the driver window fully functional with the "new," cannibalized switch? Yes? Okay, now you have eliminated the driver window switch fault (by introducing another fault - a missing switch fault - in one of the other windows that earlier appeared to (but almost certainly did not) fail. (Again, we hope that the now switch-less window is the least used window...why we will soon find out.
Okay, now, ignition switch On; set driver's master cut-off switch to "cut on", and try the other (two) window switches, starting with the next most frequently used after the driver window--usually the passenger window, the next in the daisy chain of window Up and window Down switches.
It's working now? Yes? No?
Okay, Yes (for real of let's pretend). Now go to that last (next to the last) window - you'll know it because it has a switch installed. It's working, too? Great! Now all we have is that non-failed, fully functional hole under the last un-recovered window. Now we have some decisions to make.
If we are in no hurry to give up $80 more or less, we can render that open hole non-open simply by plugging in the removed, faulty driver's switch - be sure to connect it to prevent accidental wire terminal contacts. Sure, the window doesn't work but, now, nobody will suspect just by looking at the arm rest. The only question now will be when to replace that switch, if ever. Some people like to have a back window that moves a little; some don't care. Some want to have at least two "backup" switches; for some just one is enough.
Summarizing, your only expense now is $80-90 or so (...assuming you to be a loyal Ford patron) for one switch; versus the $320-360, sans labor, you might have been preparing to spend to replace those four "bad" switches. So, by bringing three of your car's windows back to life, you actually saved a net $240-270! May I have my cut now? Oh, but wait.
What if that second (now no longer pretend) window switch that was tested (the first after driver switch replacement) had not worked. In that case, because current at the driver switch Up and Down circuits can't find a path when drawn by other switches, replacing the driver's master window cut-off switch, the only discrete component interruption in the two paths (window raise and window lower) to the other window switches should restore the switch-ability of power to those other window switches.