All of my history has disappeared

All of my history except of today's has disappeared. I did not erase my history, and really need it back. I did try to remove a couple of sites from my Most Visited, as Firefox was saving all sorts of sites I don't really visit often. In addition, I am being asked to sign in with my password at every site I go to where as before I was automatically allowed to enter, as all my passwords are saved. What happened - and how can I get back to normal? ''Contributor note: bookmarks are also missing ([/questions/1578816]).''