When you try to open the Illustartor again, it will recovered the document automatically if you have setting on for Automatically Save Recorvery data. You can set this setting from Preferences-> File Handling & Clipboard.
See screen shot for the reference. You can set the time how frequently you want to do this.
I hope this helps you
But my file was not recovered. Only the half of the content was recovered
File recovery is only a last straw kind of solution.
Don't ever rely on it as analternative to aproper backup.
A power shortage might ruin the recovery at any time.