Write about something you started but haven’t yet finished (or have no plans of finishing). You can approach this like reconciling the project with yourself, or as a love letter to the project or yourself, or, even, approach it like a eulogy for the project if, indeed, it has reached its expiration date.
If you find it helpful, start by making a list of unfinished projects, then pick one.
(And, if you do make such a list, hang onto it, and see what you can get knocked off of it, either by completing the project to done, or by deciding to let the project go for good.)