Light fixture need help

Is the junction box at the ceiling? If so you may have a feeder and a cable going down and back to the switch. This would be called a switch leg and normally the hot feeder goes to the white going to the switch, the black wire coming back from the switch goes to the black on the light fixture. The white from the same cable as the hot feeder goes to the white of the fixture,

If you have no test equipment and the breaker is off connect the fixture white to one of the cables white and that same cables black to the fixture black and turn the breaker on, if the light turns on that is the feeder or supply, if It dosent it is the 2 wires going to the switch.

Connect them as instructed above with the breaker off and when you turn it on it will work with the switch.