FAQ 8.1 - I forgot my root password... http://www.openbsd.org/faq/faq8.html#LostPW
... re: Mount the partitions. Both "/" and /usr will need to be mounted read-write. Assuming they are on separate partitions (as they should be), the following will work: # fsck -p / && mount -uw / # fsck -p /usr && mount /usr easy way (easy remember)as follow, is it right? # fsck -p && mount -a