In the game launcher please set Display mode to Borderless. THEN go here:
https://support.microsoft.com/en-us/help/2977003/the-latest-supported-visual-c-downloads
And run the x86 and x64 installers there.
IF that doesn't help, Has the game ever run OK on this computer? Or never?
IF NEVER:
Install ALL these Microsoft modules:
https://www.microsoft.com/en-us/download/details.aspx?id=26999
https://www.microsoft.com/en-us/download/details.aspx?id=52685
(run dxsetup.exe after extracting this download to its own folder anywhere on your computer)
(run dxsetup.exe after extracting from this download)
Add EU4.exe to the exceptions list of your antivirus app; ESPECIALLY if you have Windows Defender, add it to the Ransomware "Apps Allowed Through" list.
Also if you have installed RivaTuner, RadeonPro, or a gaming VPN app called Evolve, or the MSI Gaming App, or Duet, disable it as it clashes with this game.
IF IT USED TO WORK:
Please do a full **clean** re-install:
- move any valued save games elsewhere
- "uninstall" in Steam-EU4
- manually delete both the Steam/SteamApps/common/EU4 AND Documents/Paradox Interactive/EU4 folders
- re-install game in Steam, run a Steam Verify when done.
- add EU4.exe to the exceptions list of your antivirus app; ESPECIALLY if you have Windows Defender, add it to the Ransomware "Apps Allowed Through" list.
- start the game with no mods active and test
In particular make sure there are no files or folders left under either the Steam EU4 or Documents EU4 locations, before installing again.
Also if you have installed RivaTuner, RadeonPro, or a gaming VPN app called Evolve, or the MSI Gaming App, or Duet, disable it as it clashes with this game.