limp brake pedal/no brakes
 

My wife was driving my 2003 f350 6.0 diesel dully everything was normal then turned into a parking lot and the pedal went all the way to the floor...no brakes... No abs light at first. Then my truck sat for 9 months.so the batteries went completely dead. I finally got it running last night and now the abs light is on... Resivor full... No leaks anywhere that I can see... Powersteering fluid full... What do u think it is and how would I go about diagnosising/fixing prob. And on sep.should I siphon out the diesel because it sat for all that time