what happened to the "related web sites" at the top of the browser?
When you were on any specific page on Firefox at the top of the browser you had the words: "Related Links" that you could click on and get other similar web sites relating to the one that you were on. "Related Links" was located to the left of the word links at the top of the browser: (Firefox Edit View History Bookmarks Tools Window Help). It may have said: "Related Sites" or something similar.
Alle antwurden (1)
Firefox doesn't have such a menu entry. So if you had it then it must have been added by an extension.
Do you see any disabled extension in Tools > Add-ons > Extensions ?