How to reset administrator password in ServiceDesk Plus

Download the latest patch from the link provided in the comments section.
Stop the ManageEngine ServiceDesk Plus service from the Services console(services.msc).
Click the "Windows icon" and select Command Prompt (Admin).
Go to bin and run UpdateManager.bat
Browse to the downloaded .ppm file and install it.
Back up the existing build. In case of an upgrade failure, a backup file helps revert to the existing build without any data loss.
The Backup file is saved under ManageEngine\ServiceDesk\backup.
You have now successfully upgraded to the latest build of ServiceDesk Plus.
You can now start the ManageEngine ServiceDesk Plus service from the Services console(services.msc).