Corrupted file

Is the file on the cloud or a local drive or on a server? There are some kind of corruption in a read/write critical stage that is unrecoverable, these are more common when working to a network or cloud service, so would reccomend especially with large files to work locally. (And eject USB files correctly)

It may work to reneme the ending as .pdf and open in Acrobat. You will lose some of the editability, but may be able to salvage the appearance.

If it is a cloud document you can restore a previous version (see https://www.lauracoylecreative.com/illustrator-tips/illustrator-cloud-version-history for a nice explanation).