Hi maryanmeto,
I see that your file may have been corrupted or maybe encountered a problem.
You mentioned that you have it saved right do not make anymore changes on it, try and recover the file by using the Recuva program, don't worry this is a safe program, let me give you the link where to download the program it will be small and can be downloaded fast.
Recuva Downoad - File Recovery tool
Once on the website on the upper right you will see download latest version just click on that and it will ask you to save after saving run the program to be installed on your computer as soon as the installation finishes click on next then it will be asking you what type of files to recover, just select what type of file you will be recovering for it to search and show you a list of file to recover.
I hope this can help.
Thank you for choosinf Fixya,
mvincentc