The place to begin would be to read the release notes of each jQuery update.
Here's the link for 1.7 API changes. That page also includes a link to the change log.
Do this for each version you need, starting with the earliest. This will let you know not only of potential breaking changes, but also of new features that are available to you.
For the different versions, see the menu on the left from the first link I provided...
![enter image description here](https://cdn.statically.io/img/i.sstatic.net/lMAYI.png)
EDIT:
Since from the link provided in a comment, there seems to be an issue with a plugin, you'll want to check the sites of all your plugins to make sure that you're using the latest version.
Direct cause of the issue
It seems that the direct issue you're having is that you're loading jQuery more than once, and demolishing the basic-jquery-slider.js
plugin with the second load.
<!--loading jQuery-->
<script src="../js/jquery-1.6.2.min.js"></script>
<!--loading the slider plugin-->
<script src="../js/basic-jquery-slider.js"></script>
<!--loading jQuery again, which is overwriting
the original jQuery and its plugin-->
<script type='text/javascript' src='http://ajax.googleapis.com/ajax/libs/jquery/1.4/jquery.min.js'></script>
<script type='text/javascript' src='../js/jquery.ba-hashchange.min.js'></script>
<script type='text/javascript' src='../js/dynamicpage.js'></script>
You should load only one version, and load it before any plugins are loaded.
Uncaught TypeError: Object #<Object> has no method 'bjqs'
. Seems to do with the slider plugin. That would be a place to start looking. Maybe they have an updated version of the plugin.