I lost the user and password to login to the switch 3com 2928-sfp

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.
   

Adi Sunardy

• 80 Answers
• Posted on Jan 20, 2010

SOURCE: How do i Reset or break in to get reset my

The resetting of the password requires the installation of a console cable to the console port.

Be sure the terminal emulator program is set to VT-100 management using compatible, 38400 baud rate, no parity, 8 data bits and Console connection one stop bit.

Use the included cable, or be sure that the pin-out complies with a standard null-modem cable

Once the cable is connected, reboot the switch. Type a Ctrl/C until you enter the failsafe mode. This will be denoted with the prompt: “CFE>”
At the prompt execute the following commands:

CFE> passwrd
CFE> reset -sysreset

At this point the password has been reset.

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

SOURCE: i have 3Com Baseline Switch

There is usually a small button on routers that can be accessed with the tip of a pen or a paperclip. When you find that tiny button, hold your pen or paperclip down on it for approximately 10 seconds until the router resets itself to factory defaults.