title: Android Studio can't find some resources after internet disconnected
body: <p>So I am having a bit of trouble related to some resource images which stops me to develop the code. My code was working just fine, but after a few minutes without internet, somehow, Android Studio gave me an error, and it could not find 3 resources files anymore:</p>
  
  <pre><code>Information:Gradle tasks [:app:generateDebugSources, :app:generateDebugAndroidTestSources, :app:mockableAndroidJar, :app:prepareDebugUnitTestDependencies, :app:compileDebugSources, :app:compileDebugAndroidTestSources, :app:compileDebugUnitTestSources]
  C:\Users\...\Dropbox\programacao\Guia-do-Aluno-UnB\app\src\main\res\layout\activity_main.xml
  Error:(99, 26) No resource found that matches the given name (at 'src' with value '@drawable/ic_directions_car_black_24dp').
  Error:(109, 26) No resource found that matches the given name (at 'src' with value '@drawable/ic_directions_bike_black_24dp').
  Error:(118, 26) No resource found that matches the given name (at 'src' with value '@drawable/ic_directions_walk_black_24dp').
  C:\Users\...\Dropbox\programacao\Guia-do-Aluno-UnB\app\build\intermediates\res\merged\debug\layout\activity_main.xml
  Error:(99, 26) No resource found that matches the given name (at 'src' with value '@drawable/ic_directions_car_black_24dp').
  Error:(109, 26) No resource found that matches the given name (at 'src' with value '@drawable/ic_directions_bike_black_24dp').
  Error:(118, 26) No resource found that matches the given name (at 'src' with value '@drawable/ic_directions_walk_black_24dp').
  </code></pre>
  
  <p>Here is the execution error:</p>
  
  <pre><code>Error:Execution failed for task ':app:processDebugResources'.
  &gt; com.android.ide.common.process.ProcessException: Failed to execute aapt
  </code></pre>
  
  <p>I have tried:</p>
  
  <ul>
  <li>Checked the +id</li>
  <li>Cleaned and rebuilt the project</li>
  <li>ReSync the Gradle and build it</li>
  <li>Run as Adminstrator</li>
  <li>Made a clean install</li>
  <li>Changed compileSdkVersion</li>
  </ul>
  
  <p><a href="https://i.stack.imgur.com/6EOoj.png" rel="nofollow noreferrer">Here is an image of the file structure with the error code</a></p>
  
  <p>I can't build the project or run it anymore! Can you please help me? </p>