Used this procedure to get back into a Cisco 35xx switch that I forgot the enable password.

Unplug switch.
Push and hold the mode button on the front of the switch, and plug the switch in.

At the switch prompt, enter flash_init

switch: flash_init
Initializing Flash…
flashfs[0]: 456 files, 6 directories
flashfs[0]: 0 orphaned files, 0 orphaned directories
flashfs[0]: Total bytes: 32514048
flashfs[0]: Bytes used: 9057280
flashfs[0]: Bytes available: 23456768
flashfs[0]: flashfs fsck took 13 seconds.
…done Initializing Flash.
Boot Sector Filesystem (bs) installed, fsid: 3
Setting console baud rate to 9600…

Once back at the switch prompt, enter load_helper.

switch: load_helper

Temporarily, rename the current config.

switch: rename flash:config.text flash:config.backup

switch: boot

Would you like to terminate autoinstall? [yes]: yes

— System Configuration Dialog —

Would you like to enter the initial configuration dialog? [yes/no]: no

Enable with no pasword:

Switch>enable
Switch#

Rename the config renamed earlier:

Switch#rename flash:config.backup flash:config.text
Destination filename [config.text]?

Now, copy it to be your running config:

Switch#copy flash:config.text system:running-config
Destination filename [running-config]?

Fix your mistake:

Zswitch(config)#no enable secret
Zswitch(config)#enable password mysupersecretpassword

Copy the updated running config to be the startup:

Zswitch(config)#exit
Zswitch#copy running-config startup-config
Destination filename [startup-config]?

I reloaded the switch to verify I could get in now.

Zswitch#reload
Proceed with reload? [confirm]