OK, first off, crossing the wires should not have messed up anything unless you had the lights on when they touched. I can't imagine that the system is so sensative. A bulb actually shorts the wires together, but at increased resistance.
Get an ohm meter and determine which wire is ground. Then take a test light, ground to the chassis or battery with the lead end, turn on the lights, and probe the signal wire that is not the ground. If the test lamp lights, the problem is the bulb. If it doesn't light, check further up the harness until you have a good light on the tester. I doubt there is a separate fuse for these lamps, almost sounds like cold solder joints or maybe a plug/socket combo undone further up the harness.
Healthy is merely the slowest possible rate at which one can die.