title: git revert back to certain commit
body: <p>how do i revert all my files on my local copy back to a certain commit?</p>
  
  <pre><code>commit 4a155e5b3b4548f5f8139b5210b9bb477fa549de
  Author: John Doe &lt;Doe.John.10@gmail.com&gt;
  Date:   Thu Jul 21 20:51:38 2011 -0500
  </code></pre>
  
  <p>This is the commit i'd like to revert back to. any help would be a lifesaver!</p>