If you can't interact with the window at all with the code you posted (minimize, maximize, resizing, repositioning), then it sounds like your program is paused in the debugger and you need to run it by doing Debug->Continue (F5).
If you just mean the X close button doesn't close the window then the issue is the following.
Inside your switch statement you have added debug code which is preventing the default case from being ran, which probably isn't intended.
| case WM_CLOSE:
{
OutputDebugStringA("WM_CLOSE");
}break;
|
If you want the X close button to close the window, then you should either let the default case run or handle the message yourself by calling DestroyWindow for example.