When I browse the media bay for loops or sounds, I get no sound when I try to preview any of them. I also don’t get any sound when I use the Play tool on an audio track in the project window.
How can I fix this? 
it is hard to say since I don’t know anything about your setup.
a shot in the dark for the media bay is: you have control room on but not setup correctly with the outputs?
I have no idea what the “play tool on audio track” is
The same as the media bay thing.
Check your Preferences - Control Room. There is an option to Use Headphones to preview. You may have to check/uncheck this.