1 Answer

Use the arrow back option on your browser. If the arrow is missing, read these instructions on how to bring it back. 

If the menu bar is hidden then press the F10 key or hold down the Alt key to make the menu bar appear.

Make sure that toolbars like the "Navigation Toolbar" and the "Bookmarks Toolbar" are visible:

"View > Toolbars"
Open the Customize window to set which toolbar items to display:

View > Toolbars > Customize
Firefox > Options > Toolbar Layout
Check that the "Bookmarks Toolbar items" is on the Bookmarks Toolbar
If the "Bookmarks Toolbar items" is not on the Bookmarks Toolbar then drag it back from the toolbar palette in the customize window to the Bookmarks Toolbar
If missing items are in the toolbar palette then drag them back from the Customize window on the toolbar
If you do not see an item on a toolbar and in the toolbar palette then click the "Restore Default Set" button to restore the default toolbar set up. 

http://support.mozilla.org/en-US/questions/945056