I've been working on a project for several days and I saved it each time before leaving my laptop, but today when I went on the file was nowhere to be found. On the other day's when I would open Photoshop the file would be in the "recent files" tab and I could continue where I left off. I've tried searching under all my files on my MacBook but I still cannot find it.
Assuming you remember what you named the file, you can search for it using the Spotlight Search on your MacBook. It will be somewhere on your laptop unless you:
A) saved it to a server or external drive that you are not currently mounted to. This could be dropbox, or Creative Cloud files library, or
B) accidentally deleted the file, or the folder it was saved into
When such thing happens to me (I do not remember where I saved, I usually create a new document, then try to save it, to find the folder you previously saved into.)
Good tip. I've done that a few times myself.