Pip not able to find wheel
<p>I have a virtual environment. Since a couple of days I cannot run any pip commands and am getting the error:</p>

<pre><code>  File "env/bin/pip", line 7, in &lt;module&gt;
    from pip import main
  File "/env/lib/python2.7/site-packages/pip/__init__.py", line 15, in &lt;module&gt;
    from pip.vcs import git, mercurial, subversion, bazaar  # noqa
  File "/env/lib/python2.7/site-packages/pip/vcs/subversion.py", line 9, in &lt;module&gt;
    from pip.index import Link
  File "/env/lib/python2.7/site-packages/pip/index.py", line 30, in &lt;module&gt;
    from pip.wheel import Wheel, wheel_ext
ImportError: No module named wheel
</code></pre>

<p>I have wheel in the site-packages and it was installed earlier. how do I resolve this? I cannot use any pip commands.</p>