There should be a circuit breaker for them in the chassis electric bay outside below the driver. Check that its connection screws are tight.
Then, both seats should share a ground line. Check for its integrity on a ground buss in the electric bay, if you have a legend and can tell which wire it might be. It's conceivable if either seat got turned recently and it's ground connector became dislodged even slightly, then it could disable both seats. Check under both for loose connectors.
Failing a resolution following that, search and check a thread here from about December first that discussed a similar issue.
Joel