My games wont work.

Please help me
i just got this new computer 4-6 days ago, so its brand new.
i wanted to install F.E.A.R, but it wouldn't install. so i gave up on it because i just wanted to play single player while my PC was downloading GTA 4 from steam. Then later, i wanted to install battlefield 2, and it did install. i got battlefield 2 and battlefield 2 special forces. but when i got to a patch to install armoured fury, it just gave me an error sign. then it tried to install another patch, and that one failed too.

I also tried to go on steam fourms and look up the problems that i had. And a lot of people said that their battlefield 2 works perfectly fine (The one you download from Steam, i have the one that comes in a box, the full collection) So i went on steam and tried to put the registeration code in, but it didn't work. After that i just wanted to test if battlefield 2 special forces worked, so i double clicked on it. It went to this black screen, then 10 seconds later it just went back to my desktop. I even tried to restart my computer but it still wont work.

Another game i can't play is Trackmania Sunrise, but really, i dont care about that game. So its ok if it doesn't work for me.

So there, F.E.A.R can't run, Battlefield 2 can't run, and i also have Battlefield 2142, but it probably wont run too. Please help me!! How do i get battlefield 2 to work or to get it on Steam so i can download it from there?!

Did you restart between installing games? My games get really glitchy, if they work at all, unless I restart my system between installations. I guess it sets the files in right or something along the lines of that. I'd give that a try.

Alright so i uninstalled Battlefield 2 Special forces and Battlefield 2. Then i installed only battlefield 2
instead of the game opening and closing right after, bringing me to my desktop, this time it gives me a little friendly message saying

"DirectX version 9.0c or higher is required to run BF2. Please install DX9c and try again."

So then I went to this website
Downloading DirectX 9.0c (full package) to improve network security
and i downloaded that and installed it. But it still doesn't work.

Please help.