When you install MediaMonkey for Windows as a service (In the Main Menu use Options > Media Sharing and click Install as service) and an error occurs when starting the service, it is typically due to Windows Log On failure.

To resolve this:

1) Press Win Key and type ‘Services’, press Enter, locate ‘MediaMonkey’ service, double-click it and go to the ‘Log On’ Tab. Ensure that the Windows account and the password is set correct.
Note that if you previously connected your Windows account to a Microsoft Account then you will need to enter the password of the Microsoft Account.

2) In certain environments you will need to Enable service log on through a local group policy : https://learn.microsoft.com/en-us/system-center/scsm/enable-service-log-on-sm?view=sc-sm-2022#enable-service-log-on-through-a-local-group-policy

3) If you have still trouble to Log on to your current Windows account then you can Log on with Local System account, but this will fail to connect to the MediaMonkey database file from your current Windows account. In that case you might need to change the default location of your MediaMonkey database:
https://www.mediamonkey.com/support/knowledge-base/mediamonkey-install-config/modifying-the-mediamonkey-db-and-ini-files/

Note: the MediaMonkey Service is not available on Portable Installs.