This problem has afflicted me before, but I assumed it was the computer. So, when I got a new computer and plugged my Arduino in, I knew that wasn't the case.
The Arduino seems fine, or at least the lights go on. But in my Arduino IDE menu the Serial port is greyed out. The cord is fine - I've tested it with another application(not Arduino related). And, I've tried everything(adding my user to the usergroups, running as root, reinstalling, etc..). I don't want to buy another Arduino, because it seems like the usb connector is fine(the lights are on).
What should I do?
Additional info:
Also note that on my old computer it had worked, I did nothing, and the next day it, for some reason, stopped working(same issue)
Linux 64-bit Fedora 20
Arduino Uno R3
Also, I've tried building the FDI drivers for Linux, and they haven't been updated since 2009. Plus, the make fails.