Safari browser just quite showing a browser bar!

My Safari browser just quit showing a browser bar at the top of pages! So I can't type in URLs and I lost the usual navigational back button. Tried restarting, but still have the problem. My 24" Mac desktop is maxed out and so I can't load any new operating systems. Currently running Safari 5.1.10 on OS X 10.6.8. What can I do? I'm sure it won't take the very latest version of Safari. Is it possible to try and load a lower version and still get going again? If so, where can I go to get this download?