With FreeBSD 5.4 and above the booting procedure is slightly changed. Under ilder version of FreeBSD use boot -s option at Ok prompt.
However, with version FreeBSD 5.4+ you don’t have to type any command. Here is the procedure to boot FreeBSD into a single user mode to reset root password.
In this tip I will explain how to boot FreeBSD into a single user mode to reset root password.
Procedure: Reset FreeBSD root user password
Step # 1: Start FreeBSD server/workstation
Step # 2: Press Enter key at boot loader
At Welcome to FreeBSD! boot menu press spacebar key to pause default booting
Type number 4 key (type 4 number) to boot into single user mode
Next you will see following prompt from system:
When prompted Enter full pathname of shell or RETURN for /bin/sh:
Press Enter key to boot into single user mode. Next, you will be immediately dropped into a single user mode without a root password.
You need to remount / (root) file system in read and write mode with mount command, type following two commands:
# mount -u /
# mount -a
Setup a new password with passwd command:
# passwd
Next type exit command to boot FreeBSD into multi-user mode environment:
# exit
OR You can just reboot the system:
# sync;sync
# reboot
For more information read man pages of passwd and mount command.
ref : http://www.cyberciti.biz/tips/howto-freebsd-reset-recover-root-password.html