I think we all suffer from this at one time or another. The worst is when you really have a deadline for a quilt, and you just cannot get "into" that project!! YIKES!! It about kills me!
Anyway, just browse some quilting magazines or look online for a small fun project that catches your eye and imagination. Do something really small...a pincushion, needle case, etc. That may help inspire you to something. Or, try organizing your fabrics...just putting groups of fabrics together can spark some enthusiasm.
Good luck. I've been in the doldrums myself several times. Not a nice place to spend much time!! :-)