Plex media server does not open (Windows 10)

Have you ever used the (now removed) menu item to relocate the Plex data folder to a different location?
If you did, and this location doesn’t exist (anymore), then Plex will close immediately.

Please take a look into your Windows registry and determine whether the key mentioned in this article exists. If it does, either edit it to point to the right place
or
delete it to reset it back to the default location.