You can try bleeding it,but it sounds like your master cylinder has 'gone
south'. I use a 1-gallon garden sprayer (the pump-up type) ,connected to an
extra brake fluid resevoir cap with a hose fitting, to pressure-bleed the
brakes. (fill the sprayer about half full with clean fluid) Pump the handle
20-30 times. Attach a section of clear hose,a reasonably tight fit,onto the RR
bleeder screw,the other end into a container.Open the bleeder about a half-
turn,let it flow until no bubbles are visible in the hose,and tighten the
bleeder. Then do the same in the order of LR,RF,and LF. Release the pressure
from the sprayer tank,disconnect,and replace the original cap.Hope this is
helpful,have fun!

Karl