The easiest way to accidentally turn on Track Changes is to press Ctrl-
Shift-E. Press that again to turn it off.
If you have Word2007, go to Review on the ribbon, and below the big
Track Changes button there's a little arrow for a dropdown -- pick
"Accept All Changes" from that list.
In earlier versions, when Track Changes is on, the Reviewing Toolbar
appears. The blue checkmark accepts the change you have currently
selected; next to it is a tiny triangle, which gives you a dropdown
where you can choose "Accept All Changes."