sunbird

Having hit a few incorrect keys when creating a document in word I find that my web pages have become full screen and my tool bars, menu bars and task bars have all disappeared from the top and bottom of web pages. I can 'pull down' the invisible address bar using the cursor moved to the top of the screen. Web pages look slightly abnormally elongated. How can I restore the screen and reinstate my 'lost' tool bars and icons. I use an Evesham laptop (about 5 years old), Windows XP operating system and Mozilla Firefox Browser. I would appreciate any help I can get on this. I am completely stuck.