There are a couple different ways to restore your Internet Explorer address bar if it has disappeared.
My Internet Explorer address bar has disappeared! All I have is search bars from Google and Mywebsearch and Iwonsearch. How do I get it back???
You should be able to right-click on one of the remaining toolbars and select address bar again.
If that doesn’t stick, I’d suspect one of those other search bars for being spyware (not Google’s, though – Google’s toolbar is good and I run it myself). I would run a spyware tool immediately.
Microsoft recently released this knowledgebase article: The Internet Explorer Address bar is missing.
More recently updated to this: http://support.microsoft.com/kb/962963/en-us