In design won’t open a recent save file - adobe in design may not support the file format

Hi there, 

really hoping someone can help.

a file I created 5 days ago suddenly won't open? I get an error message that reads "Cannot open the file "filename.indd" Adobe in design may not support the file format, a plug-in that supports the file format may be missing, or the file may be open in another application."

I have never used a plug-in for in design so it's not that. The file gets the same error message after updating in design to the latest version, on different computer, after multiple restarts. I have also tried manually moving the file to the desktop same message. Open from bridge same message. 

no idea what has happened and there is no alternative to this file. Hopefully somebody has a resolution? 

thanks in advance