I have a dual switch in bath room, 1 for light, the other for the fan. I have power to fan but light won't work. The two switches are linked together on the bottom of switches terminals.
I've changed the switch to the light but still won't work. All other lights and electrical outlets work throughout the house.

Was it working at one point? What makes you think the problem is the switch?

My suggestion is that there is a possible bad connection in the bulb socket or even a bad bulb. Some bulbs have threads that are not true and do not go into the socket the way that they should. Also it is possible that the hot post inside the light socket has been pushed too far into the socket and the bulb does not reach it, if this is the problem the hot terminal can be bent down inside the socket with a screw driver BUT make sure the power is off to that circuit.

Ckeck voltage out of switch then to socket/Wires.