The odds are your rubber hose going to the pump is clogged. The one to the left looks empty making me believe the pump is not clogged up cause the two left cap tops are tied to the same pump. Get the carriage off the heads like you have in this photo. Disconnect from pump that clogged magenta line and hook a syringe to it...and pull. DO NOT push. If nothing comes out take the cap top out and get a paper clip, unbend it and stick it in the line and or the small hole in the cap top.