Hmmmm. It appears that the crash may have broken some links between the iMovie app and the iMovie library. The good news is that you still have your media in the project.
Try deleting preferences and see if that restores the link. To delete preferences, open iMovie while holding down the Option
and Command keys and select to delete preferences in the box that appears. iMovie will open in a new library. Reopen your old library to get back to your projects. Deleting preferences is a safe procedure that will not cause data loss or disruption to your project.
If still no luck, try redownloading iMovie. To update/redownload iMovie 10, drag your iMovie 10 app from the Applications folder into the trash, but do not empty the trash. 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. 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 and return it to the Applications folder. Now see if you can open your project and have it recognize all of the media in it.
If still no luck, try using your Time Machine backup to restore your iMovie library to a point in time just before the crash. See if that cures it. Restore the library to a different location so that you don't overwrite the current one. This might not work if it is a linkage problem, but worth a try.
All else failing, you might try contacting Apple Support. The techs there have the capability of remotely accessing your computer that we cannot do here. To contact apple support click on the Contact Support item in the upper right hand corner of this forum’s screen. Navigate to a place where you can enter your phone number.
If, after trying all of the above, the media still does not appear in the project, you unfortunately will need to start over with a newly created project. Bummer, I know. However, since you have already once done the editing procedures and have made the editing decisions, you will find that the re-editing process will go much faster. Sometimes starting over is the only solution.
-- Rich