Working file disappeared from computer when program crashed

[Shirl 0]

I have a serious problem! I was working on my file inputting information when my Nitro Pro11 just disappeared from the screen. It has done this a few times so I clicked the Nitro Icon on the desktop to open it again. When it opened again I had the recovered file and the working file. Both were identical so I closed the recovered file. When I went to save the working file, it kept saying I could not save due to another file with the same exact name was open. It didn't give me the normal option of saving by replacing the file with the same name. I closed the program so I could find the file that it said was open. The problem now is that there was not another file open that I could find and there is no file by that name anywhere on my computer!!!! This has completely devastated me since I have been working on this job since beginning with Nitro in June of 2017. I sent a message to support and was told I had not purchased Software Assurance and to go to the Forum. I have tried to find out where I can go to purchase Software Assurance for this but haven't had any luck. PLEASE CAN SOMEONE HELP ME!!!!