I found this and just had to share.. Since, I just had to recover a lost password..
Just like every other password, it is inevitable that, eventually, you will loose or forget the root password to one of your VMware ESX Server systems. So how do you reset your VMware ESX Server root password? Here is the procedure:
1. Shutdown and Reboot your VMware ESX Server
If you don't know the VMware ESX Server root password, you don't know any passwords for root-equivalent accounts, and your virtual center server also does not have it cached, the only way to change the root user password is to first shutdown / power off your VMware ESX Server.
2. Press "a" to modify the kernel arguments
As soon as you see the GRUB boot screen, press "a" to modify the kernel arguments, like this:
3. Enter single user mode
At the end of the kernel arguments command line, type "single" and press Enter, like this:
4. Change the root password
Now, change the root password using the passwd command, like this:
You will need to enter the new root password twice.
5. Reboot the ESX Server
Once you have reset the root password, reboot the server to go back into multi-user mode.
6. Verify the new password
Once the system reboots, verify that the new root password works, like this:
Resetting the VMware ESX Server root password is not difficult but you will have to bring down the server, enter single user mode, use the passwd command, and reboot to get the task completed.