Directx screenshot app

I need a program that can hook into a few older directx full screen games to take a screenshot and every example project I find doesn't work. preferably would like this in c#. Simple program when it's open a screenshot is taken and the program closes. I cannot for the life of me get this to work and it's holding me back on finishing a project. If anyone can help with this would be greatly appreciated. .net framework. I know OBS software is open source and it works on there but I don't...

Directx screenshot app WordPress ...