You will need to remove all components of Stronghold Kingdoms in all areas of your computer. You will need to make hidden files or folders visible to find these folders.

Firstly, uninstall Stronghold Kingdoms as you normally would.

The following the instructions that appropriate to your version of Windows.

Windows Vista, 7, 8 and 10
32 Bit Windows

Find and delete these folders:

C:\Program Files\Firefly Studios\Stronghold Kingdoms
C:\Users\\AppData\Roaming\Firefly Studios\Stronghold Kingdoms
(Ensure all the .dat files are deleted in this folder)
C:\ProgramData\Firefly Studios\Stronghold Kingdoms

Windows Vista, 7, 8 and 10
64 Bit Windows

Find and delete these folders:

C:\Program Files (x86)\Firefly Studios\Stronghold Kingdoms
C:\Users\\AppData\Roaming\Firefly Studios\Stronghold Kingdoms
(Ensure all the .dat files are deleted in this folder)
C:\ProgramData\Firefly Studios\Stronghold Kingdoms

Windows XP
32 Bit Windows

Find and delete these folders:

C:\Program Files\Firefly Studios\Stronghold Kingdoms
C:\Documents and Settings\\Application Data\Firefly Studios\Stronghold Kingdoms
C:\Documents and Settings\All Users\Application Data\Firefly Studios\Stronghold Kingdoms

Now download the client again from https://static.strongholdkingdoms.com/Kingdoms/StrongholdKingdoms-Setup.exe and re-install Stronghold Kingdoms with full administrator privileges.