How do i install directx and direct3D? also adobe flashplayer? ?

i already have them in my computer and installed, however when i go to play a game that i have downloaded and installed i get an error message saying something about the graphics and that i need to install the Directx and 3D .9 version or what ever and i have done it like 6 to 8 times and it still wont load my games. Same thing with the flash player?? why is this happening and how do i fix the problem so i can play my games and watch some video programs?? This is really starting to unnerve me!!! HELP!!! thanks