i'm not a writer but when i get stuck in doing anything, i let it go and attend to do other stuff. for u i guess u'd better stop wrestling with the unfinished story, maybe starting another one _which has struck ur mind lately!?_ or u can just empty ur mind totally! letting it rest a bit, for hrs, days or even weeks. and after that,ur fullrested mind automatically starts to work and build new ideas.
if u chose to start new story u can still get inspiration from outside for ur suspended story, like discussing it with other ppl, but don't force ur mind for thinking about it anymore. keep it suspended till u'r ready to go on.
and again, i'm not a writer so maybe u should hear what WRITERS tell u here, that's only some advice i thought could be useful

wish it works after all
so we wait for ur finished stories and enjoy reading em!

take care
Ana