|Try power cycling the switch (ie: unplug it, count to ten slowly then plug it back in). Also, ensure you have the most recent version of the firmware installed on it.|
If neither of those fix the issue, you could be experiencing a hardware failure.
Also, try connecting to the switch remotely using telnet. If you're unable to, then that's also indicative of a hardware failure. I just replaced two older 3COM 4400's because they stopped responding to ping and I could no longer telnet into them.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.