Truck Brake Pressure Gone?

We have a 1996 Ford Ranger 2WD. For the past two weeks there has been a scrubbing sound while driving which intensifies when braking. We took it to a mechanic and they informed us that it needed new rotors and brake pads on the front, but we tried putting the replacement off for a week until we had the money. Today, I was pulling into my driveway and the brake pressure completely gave. I had to absolutely floor the brakes to get the truck to even slow down a little. I checked the brake fluid and it was completely empty (we just added brake fluid a few days ago). So, I added more. I attempted to let the truck idle for a minute while I tapped the brakes to see if the pressure would come back. Nothing. I then noticed a nice puddle of the recently added brake fluid under the truck and the tank empty yet again. Could the brake pads just have completely gone out which is causing this leakage or is it a possibility the brake lines are now involved or something else?

Added (1). Just to reiterate: the rotors and brake pads have NOT been replaced yet. I was just wondering if this could be because of that or if waiting so long to replace them has damaged something else.

Check to see if your bleeder valve is open. Its on the brake caliper and its a little valve on the top or bottom usually. If its open take a wrench or socket and close it. If all the valves are good (one per caliper) check too see where the fluid is coming from. Look for wet spots under the car and you can find the source of the leak. Your brake lines might also be corroded. I don't think new rotors and pads would do this unless you hit or danaged something in the process. Hope that helped

You need it towed to the shop and get the work done. Not only have the rotors and pads been done for awhile, you've either blown a hose or a seal. It's undriveable.

So the next sound you'll hear is the loud rustling of many bills leaving your wallet. I'd suspect you've worn away enough backing from the remains of the pad for the piston to come out of one of the calipers. You were incredibly lucky this didn't happen on the road and incredibly foolish to drive a car with no effective brakes. Now you need at least one calipers rebuild as well as the other stuff.