I was in the OS. I was trying to disable the CD ROM and accidently selectedthe HDD. When I try to boot now it is in an endless boot cycle and does not recognize the HDD. It lists it in the Bios but when I try to reinstall windows or repair windows I get a message saying there is no hard drive installed.
Your "endless boot" expression is not clear. It could mean that it boots and reboots and reboots... with no control whatsoever from you part, or it could mean that it takes too long to boot. If it takes too long, then simply let it boot (it may be searching for the correct HDD driver, if XP can find it).Have you tried booting into "SAFE MODE"?
You should NOT need to reinstall XP, only to recover/repair. If I could base on your comment about the BIOS correctly recognizing the HDD (brand, model, port, mode, translation and size), then maybe I can GUESS what's going on.
My guess is that your Windows XP is installed on a SATA HDD and that you boot directly into Windows (system partition = boot partition).
If you were using a traditional PATA HDD, then XP can recognize it and install standard default drivers. In that case, XP would take some "extra" time to boot once, and then it should get going as usual.
But XP does NOT contain standard default SATA drivers, so you need to use an XP recover environment to boot, select "F6" to add "special extra drivers" (the SATA drivers from your motherboard's website), so XP can recognize your SATA HDD (and hence, your current XP installation).
If my assumption is correct, then you will need to search for specific methods on how to boot and add this SATA drivers (using Google, or at your motherboard's forum, or some Windows XP forum, or some "boot" forum). For "new" XP installations, there are already many articles on how to do this, but you want to recover/repair an "old" (current) XP installation, so maybe you'll need specific step-by-step instructions.
Of course, I could be wrong in my assumption.