Fuel gauge says 1/4 but tank is empty

[Shinare]

After breaking down on the highway and towed to mechanic... Mechanic called to tell me my fuel tank is empty even though the fuel gauge says 1/4 tank.

charged me $180 to tell me that (not fix the gauge). Wanted to replace sender and fuel pump but was not sure how much that would be. I told him I would just remember how often to fill up.

Anything I can look for/check on as an easy fix that would not require replacing sender? Something a novice tinkerer could check for?

I have reciently been putting the dash apart a couple times to replace radio. Could this have caused anything? Also wired in backup camera to reverse light.