My Downloads list had some valuable files and links

Valuable links?

Clearing the files out of Downloads (Ctrl+J) does not delete the file. Deletion may occur depending on where you actually download them to.

If you have anything in there now right-click on the entry and then bring up it's "Containing Folder" you can sort that folder descending on Date last modified.

If the downloads manager is still empty then check the value in about:config then filter on dir and then look at values for variables beginning with browser.download.

I located the temp file by using your suggestion and it helped. Where do I find the "about:config" option?

type about:config in the Loacation bar (where you enter websites) and enter -> it will show a warning message -> click "I'll be careful, I promise" button

Since your downloads went to a temporary folder, and there are many things that help you clean your system of "unwanted" files they may be gone.

In that case you may find the pages you got them from in your history (Ctrl+Shift+H") especially if they came from one site, or you know when you downloaded them.

The AwesomeBar search using strings from title and/or url that you use in the Location Bar also works in in your History & Bookmarks sidebars and Library List. Internal searches from the Location bar have modifiers as well to help you, but in your case you probably need to work with the Library Lists.

@ rvincent

Is your problem solved and were you able to recreate the missing downloads.