re-configuring a long-time-no-use CISCO Catalyst, or a newly purchased a used one can be tricky and considerably to have a reconfiguring before production setup.
Here's simple steps to set CISCO Catalyst 3500 to Factory Defaults.
1. "unplug" the switch.
2. while holding the "mode" button (on the front left of the switch), plug-in the power-cord.
3. issue the "flash_init" command:
switch: flash_init
initializing flash...
4. issue the "load_helper" command:
switch: load_helper
5. locate pre-config files:
switch: dir flash:
6. delete pre-config files:
switch: del flash:config.text
switch: del flash:vlan.dat
7. reboot switch
switch: boot
loading "flash:xxxxxxx"
Good to go..
