The mega-talented Bruce Coville writes:
Never throw away a story just because you don't think it's working. I have sold stories 10, 15, and even 30 years after I wrote the first draft because I finally figured out how to solve them. (Or, in some cases, because my skills finally cuaght up to my ideas.) A large file of stories that don't quite work isn't a trash heap...it's a potential treasure trove!