You will not be able to verify the project, but in any case you can create the return package. However, you can simply point Studio to the source file, when the message comes. If you don't have the source file, request it from the customer.

You also could try to open the sdlxliff file from the source folder of your project (double click should suffice) and then use "File -> Advanced save -> Save source as" to get the source file. When you have it, just point Studio to the folder where it is. If Studio will request a file with a cryptic name, use the triangle pointing down beside the file name window to select the proper name or *.* for all files.

Thanks, I will try that.