Want to recover a lost root password in OpenBSD, type boot -s at the boot prompt in OpenBSD hit enter when prompted for shell and enter vt220 as the TERM.
boot> boot -s Enter pathname of shell or RETURN for sh: Enter Terminal: vt220
Next run an fsck on the root filesystem and mount it read-write. If you have a seperate /usr filesystem then you should also mount it read-write. Finally run the passwd command to change the password.
# fsck / # mount -uw / # passwd