First thing to test is your physical connection. When you connect a computer (assuming you're working on a computer) to the network via Ethernet, does the computer see the physical connection at all? This would be shown either by activity lights around the Ethernet port on either end, or by checking through the OS. If it sees the physical connection, then you need to confirm the computer is getting an IP address at all.
Also ave you tried using a different cable, or a different device?