MS Project unable to open file

I worked with mpp file for several months but suddenly on one day I can't open it.
Error message:
The file "X.mpp" cannot be opened.
- Check that the file name and path are correct
- Check that the file format is recognized by Project
Project file saved in a version earlier than Microsoft Project 98 can't be opened.
If your file is from earlier version, open it in that version, click save as (File menu), and save in MPX format. Open the MPX file in the current version of Project. When you use this method, project data is imported, but formatting is lost.
My comments:
- MS Project 2010 SP1
- No major changes were made to the file (only operational). File was created in 2010
- Other mpp file can be successfully opened except this
- On other machine with 2010 it also can't be opened
- On other machine with 2007 asks to upgrade in order to open the file
- File name and path is correct
Please help!

Welcome to our forums.

Why are you asking about Microsoft Project here? Microsoft Project is a Windows only application and can not be run on a Mac unless it's run from a dual boot with Windows or virtual machine. In any event, you would be much better served by asking the above question in our sister forum - "Windows Secrets".

sorry, I just saw the thread with the subject Windows. and decided to ask.

Is the file part of a master/subproject or resource pool/subproject structure? Does the file contain paste links? Is the file on a remote server such that it is accessed over a network? Any of these items make a file more prone to corruption. And even if your answer to all the above is "no", files can still sometimes get corrupted. Its not easy to always identify the reason.
For starters you might try method 4 detailed in FAQ 43 found on the MVP website. If that doesn't work your best bet is to revert back to an earlier version that still opens, (you do periodically save I assume), and then go forward from there.
In that case if all else fails, you can try some microsoft project recovery tool as Microsoft project repair online service. I think that you should all get. https://onlinefilerepair.com/en/project-repair-online.html

MVP website http://project.mvps.org/faqs.htm

Thank you all for your advice! The issue has been resolved. I'm appreciative for your responses and help.