Up until recently, when I would download a pdf file, it would automatically open, and recently, for some reason, it stopped opening automatically and just downloaded to my desktop where I wanted it. I found instructions on Mozilla if files downloaded but not displayed, that included displaying my profile folder and then deleting it. I trashed it (different from deleting?) and now if I try to open Firefox, I get the message that Firefox can't open/load because profile is missing. Please advise how I can get the profile folder back in.

thanks