As writers, we all do it. We come up with a great concept, probably multiple times over in any given week, year or group of years. And then, we store them because we are very busy working on the current hot project that we just have to finish first. As time goes on, we forget those other "great concepts" and they wither and die in our files. But do they have to wither and die? No, they do not.
I have literally hundreds of these files. I consider most of them very good starting points for a great book, short story, script or stage play. I even have many songs (some sitting for almost 20 years now) that fall into this category. But they continue to sit. I think the answer to the problem lies in the question you ask about it.
Why do they sit? The simple answer I have come to on this question is that we don't make any tangible plan to go back to them when we create them. In doing this, we create a situation that overwhelms us and it becomes very easy to just ignore them and not deal with it.
What is my solution to this dilemma?
Now that I have identified the problem, the answer lies in making a plan at the point of creation to make sure I continually go back to the file and update it. I do this by putting it in my calender. I am realistic enough to know that I wont always work on it on the days I choose to in my calender, but at least I am aware it is sitting there gathering dust, and I can reschedule it for another day. If I reschedule it enough, and for reasons that aren't really justifiable, then I have to ask myself whether I really want to be bothered with it. In any event, I am either furthering it to the point that I want to work on it and find out if it is worthy of something valuable to me, or if I just need to discard it.
This works well for me in any event because I am the type that gets bored with my own stuff if I have to work on the same thing each day until it is done. I am simply the type that doesn't drown in one project until it is done. So mixing it up is something that works for me anyway and I am also the type that can go in and out of projects rapidly without missing a beat. This may not be for everybody, but it works for me.
Because I am a poor finisher, I have to be mindful that I am avoiding finishing the one I need and want to finish because that does happen a lot, so I still schedule my main project appropriately and work the file projects around that. Hopefully it is a happy balance for me and something that might also help you clear out the backlog and make something great out of that once hopeful great idea that is now gathering serious dust.
I have taken today as a starting point to weed out the ones I just don't want to persue and schedule the ones that I want to take a stab at furthering. I will continue to do that until I exhaust each file at least once and then sort the winners from the losers.