Corrupt .mprx file
Description: External causes such as crashes or anti-virus programs can damage the .mprx file in your project's folder.
Create a new project with the same language combination as the original project was.
Attach a TM to the new project.
Copy the Documents folder, and the DocumentData.sdf file from the old project's folder into the new project's folder, overwriting the current files.
Open the project - DO NOT open the document for translation.
Select the document(s) and on the Preparation ribbon, click the Confirm and update button.
Now you have a translation memory which you can use to pre-translate the original document after reimporting them.
As an alternative method, you can try the following:
Right-click on the document and export it as a bilingual (.mqxlz) file.
Import the bilingual file into a new project and continue working