Error message: "The file at location (....) does not exist!"

I was sent a proofreading project by a client but the source language was not one that I had configured on Trados Studio 2015 so I was not able to open it. To remedy this, forums told me to uninstall then reinstall Trados so that I could make my language configuration selection again and be able to open the project.

However, I am now receiving the error message "The file at location (....) does not exist!" when I try to open the project file for translation.

I cannot understand why I cannot open the file especially since before I unistalled and reinstalled Trados, I think the file would have opened were it not for the source language not being supported - there was no other error such as the above one.

The source language is Chinese - I read that the characters can sometimes not be rendered properly so perhaps this is some part of the issue.

Any help would be greatly appreciated.

Thanks,