Lost files

I’m trying not to panic, but… I just had a new hard drive installed on my computer. Had to reinstall Scrivener software. However, when I opened it I got this message.

“The project you are trying to load uses an older file format and cannot be opened. Would you like to update/ A copy of the old project will be saved in the same directory.”

However, the project I opened (which I used this a.m.) was about a month old. How do I find the one that should be saved? If I can’t find it, I’ve lost a month’s work of work!

Thanks for any help in advance.

All is well. I got some technical help locating the lost file. Thanks.