I'd un-install the whole thing, and start again. Be sure and blow away the "UserName\Documents\SH4" save directory stuff, if the un-install doesn't take it. When you go to re-install the game, it'll want to put it in "C:\Program Files (x86)\Ubisoft\Silent Hunter...". Windows "protects" that folder from all foreign invaders, including The User (which is you). You do have a choice though, during the install to pick the location AND the components to install. I usually do "C:\Ubisoft\..." (your choice though). You do not need to install the GameShadow stuff. That was the game server that Ubisoft had, and it has since been taken down. You do however, HAVE to install the DirectX 9 stuff when it comes to that, even though you have a much newer version with Windows 10. There are files in the old version that are not in the newer versions of DirectX, that Silent Hunter needs. As a side note, SSI is defunct, and Ubisoft was the developer of Silent Hunter from v2 on.
There is a post somewhere on here where someone describes how to do this... much better than me here... ratz... Just browse through THEBERBSTER's
SH4 Tutorials HowToDoIt Info thread, with all it's links to stuff. I thought it was somewhere in there...