CDR file won't open

I'm having trouble opening my cdr file. I have a poster that needs to be finished by this weekend and every time I go in to open my file it opens up as a blank document both the original document and the backup. I've gotten a file format error. I was working on it earlier and it would stop working and would automatically shut down. Can anyone please give me any suggestions on how to fix. this. I'm totally not computer literate..I can do your basics on the computer but I would need a good step by step breakdown of how to fix this. Thank you so much for your help!