At any point you can undo, or reverse, your most recent edit or edits. Click the toolbar's Undo button. (This performs the same action as selecting Edit, Undo, and is easier to use in most cases.) If you delete a character or even an entire paragraph, for example, click Undo. Word puts the deleted text right back where it was originally!
As you edit documents, Word changes its Edit, Undo menu option to reflect your last change. If you delete text, for example, the Edit menu's first option becomes Undo Clear, indicating that you can undo the clearing of text that you previously performed.
Word keeps track of multiple edits. Therefore, if you realize that the last three modifications you made were wrong, click Undo three times and Word reverses those three edits no matter what they were. If you reverse too many of your changes, just press the Redo toolbar button, and Word replaces the undoin effect, undoing the undo! It gets confusing. If you click the arrows next to either the toolbar's Undo or Redo buttons, Word displays a list of up to 100 recent changes, which you can choose to undo or redo as a group from that point forward.