folders disappearing

Hello,

I was just working on my laptop, and everything seemed normal, then I went to save something to my desktop and noticed the list of files and folders was about half as long. Sure enough, about half of my folders have suddenly disappeared from my desktop. I don't see a recent post about this within the last year or two. I have a fairly new MacBook Pro. I have tried to find invisible files, and can see them but they are not the ones that disappeared. I don't back up to icloud and so they have not gone there. I haven't done a recent backup onto an external hard drive. But I can't believe that I could just lose all those files for no apparent reason. I've had apple computers for 15 years and this has never happened. Please help!