How to change the ownership of sudoers file back to root account?

How to retrieve a root password on "SunOS PNS4 5.9 Generic_122300-42 sun4u sparc SUNW,Sun-Fire-V490". Scenario, we have accidentally edit the ownership of sudoers file on one of the SunOs server. Result we cannot use sudo command to use a superuser account.

Below is the details:

$ sudo su -

sudo: /usr/local/etc/sudoers is owned by uid 755, should be 0

$ ls -lrt

-r--r-----   1 755      root        1125 Nov 22  2011 sudoers

Currently we do not know the root password, is there any way to retrieve the root password or how we can edit the sudoers file?

Thank you.