1) Boot into single user mode, (at the FreeBSD boot loader, enter ’4′ to boot into single user mode)
2) When prompted Enter full pathname of shell or RETURN for /bin/sh:
3) Press Enter key to boot into single user mode.
4) Next, you will be immediately dropped into a single user mode without a root password.
5) Remount / (root) file system in read and write mode with mount command,
#mount -u /
6) Enter the new password with passwd command:
7) Next, type ‘exit’ to boot FreeBSD.