title: Broken php and libssl1.1 installation on Ubuntu 16.04
body: <p>I have been using Ubuntu 16.04. Recently I did some experiments with my PHP installation and I'm afraid I have broken things badly. I tried</p>
  <pre><code>sudo apt install php7.0
  </code></pre>
  <p>But it's showing a dependency and broken package error</p>
  <pre><code>Reading package lists... Done
  Building dependency tree       
  Reading state information... Done
  Some packages could not be installed. This may mean that you have
  requested an impossible situation or if you are using the unstable
  distribution that some required packages have not yet been created
  or been moved out of Incoming.
  The following information may help to resolve the situation:
  
  The following packages have unmet dependencies:
   php7.0 : Depends: libapache2-mod-php7.0 but it is not going to be installed or
                     php7.0-fpm but it is not going to be installed or
                     php7.0-cgi but it is not going to be installed
            Depends: php7.0-common but it is not going to be installed
  E: Unable to correct problems, you have held broken packages.
  </code></pre>
  <p>Following this, I ran</p>
  <pre><code>sudo apt install php7.0-common
  </code></pre>
  <p>and the response is</p>
  <pre><code>Reading package lists... Done
  Building dependency tree       
  Reading state information... Done
  Some packages could not be installed. This may mean that you have
  requested an impossible situation or if you are using the unstable
  distribution that some required packages have not yet been created
  or been moved out of Incoming.
  The following information may help to resolve the situation:
  
  The following packages have unmet dependencies:
   php7.0-common : Depends: libssl1.1 (&gt;= 1.1.0) but it is not installable
  E: Unable to correct problems, you have held broken packages.
  </code></pre>
  <p>It seems the dependency <code>libssl1.1</code> is missing so I have tried to install it manually with</p>
  <pre><code>sudo apt install libssl1.1
  </code></pre>
  <p>And here is the response</p>
  <pre><code>Reading package lists... Done
  Building dependency tree       
  Reading state information... Done
  Package libssl1.1 is not available, but is referred to by another package.
  This may mean that the package is missing, has been obsoleted, or
  is only available from another source
  
  E: Package 'libssl1.1' has no installation candidate
  </code></pre>
  <p>I am kinda stuck at this point. Did I break my os for good?</p>