The switches under 3Com 5500G- EI cannot communicate each other

SOURCE: Link and activity lights on 3Com Switch ports without connection

Do the ports work when the cables are connect?  I did some re-search and this seems to be an ongoing issue with 3com switches.  It should not effect the use of the switch

SOURCE: enter the switch configuration

page 22 of the 3com user guide for your switch talks about how to use the console cable and how to connect to your pc, I included the link below for your manual, if you don't have it:

http://support.3com.com/infodeli/tools/switches/baseline/3Com_Baseline-Switch-2916-2924_User-Guide.pdf

SOURCE: Wants to reset 3824 3com switch via console

You forget the password for the "admin" user account and can no longer perform important management operations. Use the password recovery method outlined below to define a new password for the "admin" user account:

1. Access the Command Line Interface from the console port and enter the user name "recover" and password "recover" to place the Switch in password recovery mode. The Switch remains in password recovery mode for a maximum of 30 seconds, before it returns to the CLI login prompt.
   
   You must use the console port to recover the passsword. If you attempt the recovery method using the network, the password will be rejected.
   
   
2. Perform a hard reset on the Switch whilst it is in password recovery mode by switching it off, waiting a few seconds, and switching it on again.
   
   You cannot use a soft reset operation to reset the password of the "admin" user account. This will end the password recovery procedure and return you to the CLI login prompt.
   
   
3. When the Switch has rebooted following the hard reset enter a new password for the "admin" user account.
   

SOURCE: i cann't connect to my switch

Your superstack 3 should have a 9 pin male connector at the back labeled "console port" you need to connect this to your serial interface on your pc or laptop. With 3Com you also need to set your baud rate to 19200 as this the default for 3Com.

SOURCE: i forgot my admin password

If it's the Power Plus (3C16475BS) model, there should be a reset button inside a small hole on the back. "10 - Recovery Button" Inserting a paperclip or similar to reset. If it's not the Power Plus model and is in fact (3C16475A), this is an unmanaged switch, with no administrative capabilities. You don't need a password.
http://www.3com.com/products/en_US/detail.jsp?tab=features&pathtype=purchase&sku=3C16475BS