title: Undo git pull, how to bring repos to old state
body: <p>Is there any way to revert or undo git pull so that my source/repos will come to old state that was before doing git pull ?
  I want to do this because it merged some files which I didn't want to do so, but only merge other remaining files. So, I want to get those files back, is that possible?</p>
  
  <p>EDIT: I want to undo git merge for clarification.
  After seeing some answers, I did this </p>
  
  <pre><code>git reflog
  bb3139b... HEAD@{0}: pull : Fast forward
  01b34fa... HEAD@{1}: clone: from ...name...
  </code></pre>
  
  <p>Now, what should I do ? Doing <code>git reset --hard</code>  is OK ? I don't want to screw it again, so asking for detailed steps ? </p>