Internet Troubleshooting is hard......YOU need to explain the situation accurately and WE need to listen/understand what you're saying........Throw in a little ESP and we've got it made......
What kind of and brand of Bathroom light fixture........incandescent?......over the sink?......in the ceiling.......
And you say YOU replaced all the wiring and the Circuit Breaker.....? That's pretty tough to do....any explaination.......?
And the light switch....new wire?....new switch ?.....in the wall "Normal" or attached to the fixture?
And the wiring is grounded ?
Metal or plastic (boxes)?
And does the circuit have a GFCI outlet on it........
Are the bulbs REALLY blown ? .....have you ever checked them "after" in a different light.....?