Create an inspiration book/box/folder/bulletin board.
Every artist hits a creative wall from time to time. Some will tell you to just work through it, and eventually you'll get your "art mojo" back. But it's really hard to make anything when your mind is like a blank page. Just figuring out what art supplies to fiddle around with can be frustrating when you have no ideas at all.
My solution is an inspiration folder. Anytime I find an image that really strikes me--I like the colors, or the idea behind it, or it always sparks fresh ideas when I see it--I tuck it into a small folder that has a bunch of clear page holders. Pictures from the newspaper, magazines, fliers, brochures from museums, random stuff I find. I never know where I might find that next inspiring image. When I get stuck in an artistic rut or am at a loss for new ideas, I just page through my inspiration folder. Something always catches my eye and renews my creativity.