Convert published project to cptx?

Is it possible to reverse-engineer a published Captivate 7 project to make it editible in Captivate?

I was saving my file after making a major change when I dared to try to switch to another programme, CP crashed and destroyed my file. I've tried the 'retrieve from cache' suggestion which hasn't worked.

I do have a backup on another server but will have lost a day's work if I can't get my file back.

Any suggestions greatly appreciated.

Thanks.