strange thing with .ai

[ConstancaLopes]

I've no idea what happened with .ai file, but some days ago it denied opening. I didn't see any errors or something. Till today I cant solve this trouble.

[ColtonHayden]

Then you can't open .ai file via any method apply more powerful solutions as recover damaged adobe illustrator files

This one blog is very interesting, it is related your issue - http://smallbusiness.chron.com/recover-work-illustrator-39270.html

It is the source of guide below: https://helpx.adobe.com/illustrator/kb/troubleshoot-damaged-illustrator-files.html

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.

[Telecaster]

I've no idea what happened with .ai file, but some days ago it denied opening. I didn't see any errors or something. Till today I cant solve this trouble.

Have you tried rebooting your computer? Sometimes an app will leave a "lock" on a file—it's way of saying "I own this, don't touch!"—that prevents anything, sometimes even the app itself, from opening the file. A reboot usually clears this up.

-Dave-