dome light problem

i need help with my dome light. my vehicle is a 1985 s10 blazer. i cant get my dome light to come on unless i ground the light directly to the body. there is no other way that i can get it to turn on. what might my problem be?

To turn the dome light on the white wire from the dome light is grounded by either of the door jam switches or the headlight switch. there probably is a break in the white wire or all the switches are bad, being that old that is possable

thx ill have to try replacing that wire when i get the chance, ill let you know how it goes