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).
Telion's answer was helpful to me in the past, but today it took me an hour to figure out that after some copying and pasting from other projects, my audio track had some Track Keyframes (notice the difference from Clip Keyframes) that were causing the volume to be 0.
So, I switched into the Track Keyframes mode and then used the Pen tool to highlight all of those keyframes, and I deleted them.
I used to solo the tracks, and then the audio would play and that usually does the trick. This time, that didn't work. After several restarts and quitting Premiere, I gave up and duplicated my project. Now audio works!