Did you change the file link in your document from 1.6.4 to 1.7.2? Code in the header should be something like:
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js" type="text/javascript"></script>
if you are linking to the google library or
<script type="text/javascript" src="scripts/jquery-1.7.2.min.js"></script>
if you are hosting the file on your site.
Re-check your file paths and that the file(s) you need are actually saved within your site.
Chris
