Mods are not stored in the Conan folder. And some mods are old and break the game.
Look in steam / userdata, for a subfolder named 440900 delete everything in that folder.
Then try to launch.
If that doesn’t work uninstall the game, then delete the 440990 folder in located steam / steamapps / workshop / 440900.
Then reinstall the game, launch without any mods, if it launches this will verify it’s a mod issue.
If it still wont launch then send a report to Zendesk.
If the game launches you can, carefully reinstall mods one at a time, I would pay attention to the last time the mod was updated, and the comments from other players about the mod.