People always tell me that they are stuck for ideas. They can't think of what to write. I've never had that problem myself. Sure, sometimes I don't know which direction to take a story or I get stuck on a character's motivation...but an idea is the spark of something, an inkling. My problem is having too many ideas and not knowing what to do with them. Or rather, not having the discipline to carry them out.
You can't grope a well-written story out of thin air. What you get out of your ATM only complies with your credit balance. If you want a brilliant tale, you have to stock up. Just like with a vending machine. You can't shake that thing and pray something pops out every time. Especially if it's empty. You have to stock it yourself.
Wait, stock the machine, operate the machine, pay for the machine and use the idea ATM all on my own?
Not necessarily. You can always collaborate with friends and fellow writers to come up with ideas and writing prompts which you can store in one place, whether it's a word file or a box filled with slips of paper. Of course, everything in the box is fair game for whomever decides to use it.
However, ideas are sparks. What you do with it is what is really imporant.
Next time you are stuck for an idea, remember that you can't hope to catch a fully formed plot. You need to ignite a spark first, even if that spark is seemingly simple and unoriginal.
Ideas are free. Developing them into stories is hard.