Recovering root password on Solaris SPARC server:

1.Bring the server to OK prompt. 
If the server is up and running then login to server console,you can initiate the reset or send break signal to bring the server to OK prompt.

2.Boot the OS in failsafe mode from OK prompt.
#ok boot -F failsafe
3.Once the server is booted up in failsafe mode,then mount the root disk in /mnt .
If you don’t know the root disk,then execute format command and check one by one.
#mount /dev/dsk/c1t1d0s0 /mnt

4.Take a backup of /mnt/etc/passwd & /mnt/etc/shadow file before removing the root password from it.

# cp -p /mnt/etc/passwd /mnt/etc/passwd.13092013

# cp -p /mnt/etc/shadow /mnt/etc/shadow.13092013

5.Now remove the encrypted password entry for root from /mnt/etc/shadow file using vi editor.You may need to set term to edit the file.(For bash shell — >#export TERM=vt100)

Before Modifications:

#grep root /a/etc/shadow

root:XD9erIqDGXYM.:12192::::::

After Modifications:

#grep root /a/etc/shadow

root::12192::::::

6. Update the boot archive to ensure boot archive is up to date.

# bootadm update-archive -R /mnt

Creating boot_archive for /mnt

updating /a/platform/sun4u/boot_archive

7.  Reboot your system using init command.

# init 6

Source:http://www.unixarena.com/2013/09/how-to-breakrecover-solaris-root.html