How to Find the IP address of a 3COM switch ?

I connect my 3COM 4200-28 port switch for configure through ethernet ,at that time wrongly i enter the switch MAC address in the switch bridge database folder.At that time i loss the communication with switch .After that i try to access the switch through the console(serial)port.So I can’t access the switch anyway neither ethernet nor Serial port.
Please any one help me how can I access again the switch.

Through this switch i can connect other device.But i can,t accesss the switch itself.