Audio not playing in timeline also another thing

I'm having a problem with audio not playing in the timeline. I probably toggled something using an avid keystroke or I don't know what. Any suggestions? I can load the audio from the timeline into the source window and it plays out loud.

Also Premiere crashes and locks the drive, or just locks the drive. I try and save and it says " you do not have permission to access this drive." If I alt tab to finder and try and create a folder I get an -50 error. I have to re-boot. After the first time I altered the permissions to ignore ownership.

Premier is not being my friend.

Ok first part solved master volume got turned down to -98. Now what is crashing making the drive goof the permissions?

What version of Premiere, OS and model of computer? Do you have a Matrox driver installed?

Finder error -50 can occur when OS X thinks a disk or folder is in use. As it keeps occurring I'd recommend checking for apps running in the background like TechTool that may be locking up resources.

My software:
Pro Maintenance Tools - Tools to keep Final Cut Studio, Final Cut Pro X, Avid Media Composer and Adobe Premiere Pro running smoothly and fix problems when they arise
Pro Media Tools - Edit QuickTime chapters and metadata, detect gamma shifts, edit markers, watch renders and more
More tools...

I got rid of the USB drive, and that stopped the error -50 crashes. Still very unstable, I had updated another drive to Yosemite and I tried working with that, and it's stable. Although now I cant use my Matrox card because they havent created Yosemite drivers yet.

The Audio problem was some sort of pilot error, some muscle memory keystroke that turned the audio down to nothing on the master mix.