All of a sudden all the text in my vi editor is highlighted.I have no idea how this happened. Please help.
This could be a variety of things. Its most likely because you are visual select mode (which you get to by pressing the 'v' key in command mode). Try pressing Esc twice to see if that gets you out of it. Another clue on this would be that it would say -- VISUAL -- in the status line.
If that's not it, giving us a bit more info would be in order, such as what you were doing at the time, if closing the file and reopening fixes it, etc.