If you keep a Time Machine backup you could restore your iMovie 10 app and library from there.
At the time that your Mac crashed, and you then wiped it clean, where was your iMovie 10 library stored. On an external drive? If so, you would still have your iMovie library intact, and that is where all of the projects and media are stored. You would just need the iMovie app to play the projects. You could plug the drive into a Mac that had iMovie and open the projects from there. In the event that the Mac was running a newer version of iMovie than was used to create the project, the library would be updated when it opened. It then would no longer open on the older iMovie app version.
You can try this procedure to see if by chance you can get iMovie: To update/redownload iMovie 10, drag your
iMovie 10 app from the Applications folder into the trash, but do not empty the trash. (You can skip that step if you had iMovie 10 on your computer before, but deleted it.) Sign in to the app store and open your purchases folder by clicking on your name at the bottom of the app store side bar. (NOTE: For El Capitan and older, click on the Purchases tab at the top of the app store screen and then sign in. Click on Purchases again to reveal your
purchases.) You will see your purchases displayed, including iMovie 10. Redownload/update iMovie from there. If not successful, drag your present iMovie app out of the trash (if you moved it there) and return it to the Applications folder.
Try the above procedure using first your new Apple I.D. and then your old Apple I.D.
-- Rich
