Hi there hope i can be of assistance.
As you have checked the basics, the bulbs/fuses we now need to check the output of the headlamp switch and the low beam relay.
Firstly the switch needs to be checked to ensure that the internal contacts are ok, and that it is sending 12v to the low beam relay which activates the lights. if the switch is ok then it is likely to be the low beam relay that has failed.
If you need any further assistace please help, cheers Bob
UK Car Mechanic
Nvq Level 3, ATA technition, Ford technition,5 years with Ford, 3 years with MG Rover