Let me give you the possibilities.
1) Your pickups are screwed!!! Pay big money for replacements!!!
2) Your volume pot is screwed, change em!
3) Your pickup selector switch is screwed, change em!
4) Your output jack is screwed, change em! (an electric guitar got output jack and no input. signal comes out and not go in from the guitar, heh... one of my pet peeves)
5) There is a random broken wire at some point, connect!
If you are not able to trouble shoot this, send it down to our good friend Beez at Guitar77, Peninsula/Excelsior basement.