Your saves are typically located in %USERPROFILE%\Saved Games\Portal Knights . Back this up before applying any future patches.
This is usually solved by installing the latest DirectX or the specific C++ Redistributable version mentioned in the error. Portal Knights Free Download (v1.7.2 & ALL DLC)
Open the extracted folder and check the DLC or Add-ons directory. Version 1.7.2 usually bundles all previous content, including the Druid and Rogue classes. including the Druid and Rogue classes.