I tried one song, it shows the green plus like I can but nothing
Ok, now I am starting to think that there may be permissions issues or something...
Try right clicking on one of the files and telling it to open in iTunes, see if it plays then.
Then, and I cannot believe that I am recommending this, go into Disk Utility (Applications -> Utilities -> Disk Utility) select your boot drive from the sidebar on the left and then choose 'First Aid' from the tabs up top and finally, choose to repair disk permissions.
Also, if you get this in a reasonable amount of time, email me and we might be able to set up a screen sharing session