Adobe illustrator file corruption.

Hi, I’ve gotta problem with my Adobe Illustrator. Yesterday I was working in it. But today it doesn’t want to open this file. It says that the file is corrupted. What’s the matter? I did nothing wrong. I’ve saved it as usual and then switched off my PC. It’s bad that I’ve got no backup. I had no idea that it could happen. Help me please to recover this file. I don’t want to work all day again. The size of file is 42 428 kb.