Margins have always been frustrating to deal with, and they are even more so in Word 2010 because the options to change or reset the margins are hard to find.  Take a look at the screenshot below to give you an idea of how to work with margins in Word 2010, and then follow the directions below that apply to you (to reset margins, or to find where to create custom margins):

To reset margins to Word 2010 default page margins:

1. Head to the navigation bar at the top of MS Word and click on the “Page Layout” tab.
2. Click on the “Margins” icon.  It should be around the third item from the left.
3. Scroll down on the list of margin options and left-click on “normal”.

Your margins should now be reset to the Word default margins.

To create custom margins in Word 2010 (and my heart goes out to anyone playing with margins in Word):

1. Head to the navigation bar at the top of MS Word and click on the “Page Layout” tab.
2. Click on the “Margins” icon.  It should be around the third item from the left.
3. Now click on the “Custom Margins…” option at the very bottom of the list.

You should now be able to enter your custom margin settings.