I feel stupid, but... Usually, you have a bar at the top left of your computer, which includes history, bookmarks, tools and other stuff. I have lost it, and can't find how to get it back. I believe I turned it off to get more space on the screen of my laptop (11"6 Acer, win. 7, 3Gb of RAM) and never thought it could be hard to restore it. Any ideas? thank you for your help.