Passenger Rear Brake not working?

[SHOguy 92]

all my brakes work except the passenger rear brake don't make any noises or nothing it just don't work and my ABS light is always on and the ABS isn't working but i was just thinking maybe thats because that rear one isn't working and if that got fixed it would work fine again.
Thanks
Josh

 

[Rob94]

Frozen slider pins.....plugged brake hose.....bad proportioning valve. Could be any of the above. Get under there and start checking things, or take it to a shop if you don't have the know how. Brakes are nothing to ignore.