[Cannot create new scenarios]

How do i get ObjData if it is missing? Also if it was custom scenery, why do i sometimes get red error messages with the text "Cannot load: [Random letter and number string] on the title screen of OpenRCT2?

Also i'm not trying to access a save game, i'm trying to create a new scenario, but the game will not create it.

[Cannot create new scenarios]

Hello, i am having a problem where, no matter which OpenRCT2 installer i download, when i try to create a scenario it either crashes or sends me back to the main title screen. Any help would be appreciated.