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It is the source of guide below: https://helpx.adobe.com/illustrator/kb/t...
Place the damaged Illustrator file in a new Illustrator file.
Important: This solution doesn't work if you didn't select Create Compatible PDF File in the Illustrator Native Format Options dialog box when you saved the original file. On the Macintosh platform, the damaged Illustrator file may appear dimmed in the Place dialog box, but you will still be able to select it and place it in the new Illustrator file.
1. In Illustrator, choose File > New.
2. Select the appropriate size and color mode, and then click OK.
3. Choose File > Place.
4. In the Place dialog box, choose All Formats from the Files of Type pop-up menu (Windows) or choose All Documents from the Show pop-up menu (Mac OS), choose the damaged file, and then click Place.
5. Name and save the file.