My work involves dealing with a lot of text. It could be anything starting from a piece of code, document/agreement, script to even the short essays I write about my blogs. Often these texts evolve over a period of time and every time one opens them, we add/remove some text from that. Some of these changes are for good, but some unknowingly degrade/spoil the text. So to revert back to the previous copy I use Version systems.
1) Word Documents have tracking feature which records who added what and when.
2) Online documents can be typed in a Twiki (enterprise Wiki) which tracks the changes.
3) I put all my code and scripts in CVS (Concurrent Versions System)
However sometimes some text files or scripts escape these processes and I have a hard time tracking and undoing the changes there. In that case I use WinMerge (or VIM-Diff) It compares the text of the 2 files and highlights just the lines which are different. Hence making my job of reviewing the edits much easier.
As far as possible, I like to have a version system. I enable tracking on all Word Documents, I have Twiki