There is lots of information to recover lost passwords on the Cisco Website. Most, if not all, involve having console access to the router - but say the router is on the other side of the world? Answer - Use 3 simple steps via SNMP...
1. Read the config to a tftp serverà
"snmpset -c <write community string> <routerIP/name> .188.8.131.52.184.108.40.206.1.55.ipaddress.of.tftpserver octetstring <filename on server>"
2. Next edit the configuration substituting the new, plain text, enable secret password and save it back to a tftp server on the same network as the router.
"enable secret <new password>"
3. Then tell the router to boot the config on your tftp server (tftp server needs to be on the same subnet)à
"snmpset -c <write community string> <routerIP/name> .220.127.116.11.18.104.22.168.1.50.ip.address.of.tftpserver octetstring <filename on server>"
And the new config is running, telnet to the router and try your new passwordà then copy the running config to startupà
Hope this is of some use to someone somewhere... Good Luck.