In latest version of Microsoft Word, 2013 the default Ruler measurement unit has changed from inches to centimetres. If you prefer inches, here is how you can change it back easily.
In Word, click File
Click Advanced and scroll down to Display. Click in the Show measurements in units of”: list box and select inches
Click OK and you should see the classic ruler:
I personally was having some problems using the centimetre measurement when setting tabs in a document, so I needed to go back to inches.
If you don’t see the option to turn on the Ruler, look under the View tab within the Show group.