The circuits for dial gauges usually involve some kind of sensor and either a voltage or amperage needle-type gauge.
Power from the battery either
(A) goes to the gauges first, then to the sensors and then to ground, OR
(B) to the sensors, then to the gauges, and then to ground.
If (A), there's probably a common supply wire from the battery which supplies all of the gauges, probably through a fuse.
If (B), there's probably a common ground for all of the gauges.
If your gauges are wired as in (A), then you may have a bad ground somewhere. If they're wired as in (B), then you may have a blown fuse or bad connection to the dashboard circuit board.
It's probably more likely that a ground went bad, than a supply wire.
This is probably easy to fix if you can find the problem. Start at the dashboard circuit-board/instrument-cluster-box and start back-tracing the wires that are attached to it. The wires may be bundled and taped together, making that difficult.
Maybe flusher can provide some information about the colors of wires running from the instrument cluster to 12V or to ground.