Hey
@Fay1, thanks for reaching out to us about this.
Even though Dropbox wouldn't delete your files on its own, it sounds like you enabled the computer backup feature on your Dropbox application.
You can disable the feature, by following the steps
here.
As for your deleted files, do you see them in your
deleted files page here in your Dropbox account?
Can you also check your
events page, to see if you can find out more info about the deletions?
Let me know what you find.