headlights not working

i have a 1996 sentra and ever since my uncle worked on the brakes my headlights wont come on, and my brights wont stay on, and my parking lights wont turn off. so i have to undo the battery every time i park it for a while, and i have to hold my bright on the whole time i drive. i checked the headlight fuses under the hood and the "fuseable links" werent melted... at least they didnt look melted. i would really appreciate any help or ideas. thanks,
heather

wiring would be my first bet.