Combination meter nice person.

hello,
i have an 08 model and want to say i have never had any problems with it, until last week when my dash did not come on, thought maybe it was a glitch so i went on to work, about a 10min. drive, when i got there it would not shut off. after locating the phone number to my dealer, i called and they said it would take a couple of days to order the part. took it in they replaced the part and my wife took it home on friday, monday i started on my way to work and thats when i noticed left headlite out, license plate lites out, the maint req'd lite was on, just changed oil two weeks pryor, fuel tank was full but only showing 7 tenths,and last but not least my gas mileage had gone from 46 to 47 mpg, down to 37 to 38 mpg, so i called the dealer and he said they had never heard of such a thing, but bring it back and would be glad to check it out. well after some thinking i went online to look up prius problems and problems with the combination meter nice person., i found different thing it might be but none fit exactly my problems, then i stumbled across directions on how to install that part and it said first thing to do was disconnect battery.. all things this part controlled was electrical, so i said to myself "self" i bet that high educated man didn't disconnect my battery so i tore my truck apart to get to the battery and disconnected it for about 30min then reconnected it and went and filled up with gas and went back home, got a glass of tea and went back out for a 30min drive, gas gauge started working, and i got 49mpg on my little stroll, hopefully this takes care of my problem and helps someone else, after tomorrow, i will come back on here and let u know my results........................