user12624: I'm importing .MP4 file which has music in it, but in Premiere there is no audio track at all.
I have restarted PC, installed K-lite codec pack, Quicktime codecs but why? Why is it so hard to simply import an .MP4 file with music to the video editor?
I searched the internet a lot but only find useless advice

user12624: Ok, here is answer. 
Quote: 

Please clear the Media Cache (keeping Premiere Pro closed). Find
  instructions here: FAQ: How to clean media cache files?
Navigate to the Media Cache location as specified in the Premiere Pro
  preferences and rename the folders.
   MAC: Premiere Pro menu>Preferences>Media
   Windows: Edit Menu>Preferences>Media

Please reply if your issue gets resolved after trying these steps.
NOTE: Premiere Pro will conform all files after opening any/all
  project(s) and will generate the peak file for the audio. This might
  take long depending upon the number of Media used in the project(s).


12624: <p>I'm importing .MP4 file which has music in it, but in Premiere there is no audio track at all.</p>
<p>I have restarted PC, installed K-lite codec pack, Quicktime codecs but why? Why is it so hard to simply import an .MP4 file with music to the video editor?</p>
<p>I searched the internet a lot but only find useless advice</p>
 12624: <p>Ok, here is <a href="https://forums.adobe.com/message/9109650#9109650" rel="nofollow noreferrer">answer</a>. 
Quote: </p>

<blockquote>
  <p>Please clear the Media Cache (keeping Premiere Pro closed). Find
  instructions here: FAQ: <a href="https://forums.adobe.com/thread/2152942" rel="nofollow noreferrer">How to clean media cache files?</a></p>
  
  <p>Navigate to the Media Cache location as specified in the Premiere Pro
  preferences and rename the folders.</p>

<pre><code>   MAC: Premiere Pro menu&gt;Preferences&gt;Media
   Windows: Edit Menu&gt;Preferences&gt;Media
</code></pre>
  
  <p>Please reply if your issue gets resolved after trying these steps.</p>
  
  <p>NOTE: Premiere Pro will conform all files after opening any/all
  project(s) and will generate the peak file for the audio. This might
  take long depending upon the number of Media used in the project(s).</p>
</blockquote>
