No brakes!!!

[08TR196]

Wife drove her truck yesterday and not one issue...
today she has no brakes. I checked the fluid and I'm going to try and bleed the brakes but would like to know what else I need to check>

I was in her truck yesterday going to church.. so I don't get it.

The brakes push all the way down to the floor..
when you pump them they seem to build pressure but loose it..

[65comet]

Ok, here's everything I'd check in order.
Look all over the master cylinder for a leak.
Follow each brake line from master cylinder to each wheel checking for a leak.
Take off each wheel one at a time so you can clearly inspect each ones brake components.
The flex line from the hard line to the caliper has no leak.
The caliper isn't leaking.
The rotor and pads aren't so worn that the pistons in the calipers haven't extended out beyond their cylinders and are leaking.
If the rears are drums and not rotors, remove the drums to inspect the wheel cylinders for leaks.
If no leaks seen at this point, then I'll do a good bleed job.
If still mushy pedal, if the fluid got real low in the master cylinder, I'd take it off. Not only to try and bench bleed it, but to also see if it is leaking at the pushrod and into the booster. Thus hiding the leak.
If you still have a problem, then come back and post. We'll get into the rarer possibilities.