After replacing the front brake pads on my expedition, I discovered I had no brake pedal. I tried to bleed conventionally but with no sucess. Can anyone offer any help???

 

keep the master cylinder full and open the bleed screw and let them drain. this will bleed out the air. just make sure the master stays full.
With abs i bleed my brakes the drive my truck and do some hard stops so the ABS pump kicks in and then i go back andrebleed my brakes.
Here is a link on how to bleed brakes.