Let's consider the possibilities one by one.
The auxiliary relay is common to both 12V outlets, but it feeds almost every other accessory. You would have a lot more problems to report if it was not working.

Next is one of the big connectors between the fuse box and harnesses. Once again, a failure here would affect lots of other things.

As suggested, there is a separate fuse for each outlet (#30 and #36). Very unlikely they would fail at the same time, plus they feed other things (like the radio and power seats) you would notice. Worth a check, though.

Next comes a connector located under the console just behind the shift lever. This is where I would place my first bet. This connector not only feeds the outlets, but seat heaters as well. If you have heated front seats, see if they actually get warm. Have you had any repair work done in that area (like the parking brake handle) lately? This connector, when disconnected, breaks both the hot and ground wires of both 12V outlets.

Last is a ground connection at the doorsill that is common to both outlets. I would call this the dark horse.

Use your voltmeter to check for 12V relative to ground rather than to the outer ring of the 12V outlet (ignition ON). If 12V is not there, the fault is on the hot side. If there, check resistance (ignition OFF) from the outer ring of the outlets to ground. This will tell you if there is a break on the ground side. Also check resistance between the outer ring on one outlet to the outer ring on the other.

There is also the possibility (already suggested) tht wires have fallen off the outlet terminals. It seems too much of a coincidence that it would happen to both at once, but not impossible.
Let us know what you find.