VMware Appliance password expire :-

Unlocking a locked out root account

If the root account is not accessible via the console, the secure shell, and the Virtual Appliance Management Interface (VAMI) (vCenter Server Appliance 5.5), the root account has been inactivated due to password expiration. To reactivate the root account, the vCenter Server appliance must be rebooted and the kernel option modified in the GRUB bootloader to obtain a root shell.

1. Reboot the vCenter Server appliance using the vSphere Client.
2. When the GRUB bootloader appears, press the spacebar to disable autoboot.
   
   Note: If the time between when you power on the virtual machine and when it exits the BIOS or EFI and launches the guest operating system is too short, you can adjust the delay.
   
   
   
3. Type p to access the appliance boot options.
4. Enter the GRUB password.
   
   Note:
   
   • If the vCenter Server 5.5 appliance was deployed without editing the root password in the Virtual Appliance Management Interface (VAMI), the default GRUB password is vmware.
   • If the vCenter Server 5.5 appliance root password was reset using the VAMI, then the GRUB password is the password last set in the VAMI for the root account.
5. Use the arrow keys to highlight VMware vCenter Server Appliance and type e to edit the boot commands.
   
   
6. Scroll to the second line displaying the kernel boot parameters.
   
   
7. Type e to edit the boot command.
8. Append init=/bin/bash to the kernel boot options.
   
   
9. Press Enter. The GRUB menu reappears.
10. Type b to start the boot process. The system boots to a shell.
11. Reset the root password by running the passwd root command.
12. Restart the appliance by running the reboot command.