Get WizTree, it's free: https://diskanalyzer.com/download

I got the portable version so I don't have to install anything, and see where your Poser Runtimes are. They should be a few hefty Gb.

You might have accidentally drag-n-drop the Runtime folders somewhere else... in a nearby folder? Look in the Recycle Bin... under it LOL!... they gotta be somewhere.