2001 jeep cherokee limited 4 . switched to brights and when I turned the off headlights were out. dashboard lights , running lights and brake lights ok, both fuse boxes ok. whats next
Check the low beam relay in the fuse box under the hood.
Tester
True story…
Several years ago I had to use my wife’s car in the evening for a short trip. I noticed as it got darker that the low beams weren’t all that great. I switched to high beam and they weren’t as bright as I had expected they’d be, either.
I stopped the car with low beams on and got out to look at them. One side was out because a low beam filament had burned away. I threw on the high beams and took a look. The high beam on the opposite side was out because the filament had fried. 
Long story, short version, had my wife kept driving she eventually would have had no low beams and/or no high beams as another light burned out. She was one filament short of total darkness.
Two new bulbs fixed it. Wow! I could see! Not sure if it helped my wife, ha, ha… 
Unless one checks frequently or drives where it’s dark (and is observant) this is what can happen.
So, if a temporary relay swap (with another of the same part number in a non-critical location in the fuse/relay box) doesn’t do it then examine the bulbs carefully.
CSA
That’s not nice to say about your wife.
Yosemite
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“She was one filament short of total darkness.”
It’s Okay. She’s a Trophy 
Wife!
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