There are 8 entries shown for SketchUp exe running, and the Task Manager dialog has many more entries.
They seem to be running but not opening the main SketchUp window.
Try 'killing' all of the 'SketchUp' entries and retry...
I also see that your system dialogs display using oriental characters [Japanese?].
What is your Windows user-name ?
If it's in similar characters I am wondering if that is causing problems with reading some file info.
Your user's SketchUp Plugins folder and certain 'preferences' files are located in your 'AppData' tree.
e.g. C:\Users\YOURUSERNAME\AppData\Roaming\SketchUp\SketchUp 2018\SketchUp\Plugins
It's hidden by default...