You obviously have problems, because if a car sits it just doesnt loose fluid, there is some kind of leak. First off check the whole clutch assembly, and look for leaks. Maybe you dont have leaks, maybe it was low when you parked it and there was air in the system and the fluid could have settled into the system where you had air, now you have no fluid in the master cylinder and you need to add fluid and bleed it. But if you bleed it and you still ahve no pedal and still see no leaks, it is you master cylinder and your seals have gone inside of it and it is not making pressure, so that will need replacing, it could be rebuilt but you will spend more money and time than if oyu just bought a new one to throw on it. First off bleed the system (get a friend to help it will be much easier) then let us know what you find out.