i was just trying to play a new game and it said i needed to reinstall Direct X, so i did. And when i rebooted my computer, i get a black screen! Help plz!

Try booting into Safe Mode options:

After the power-on and BIOS POST or your Logo screen repeatedly tap the F8 key or hold the Ctrl key before Windows starts.

Then try a System Restore to a point prior to the problem.

I tried that, but it doesnt get that far. I get the logo screen but the only thing that shows after that, even when i press ctrl or f8, is a black screen with a flashing dash in the upper left corner..

Do you mean your computer logo or XP?

If XP then you've gone too far. Press F8 prior to Windows (XP).

If you mean your computer logo goes straight to the blinking cursor then check your BIOS Setup (press Delete at power on) and verify that your hard drive is detected and in the boot menu.

its the computer logo... i tried delete at power on but nothing happened. just brought me back to the black screen with the blinking cursor.

What is the make and model of the computer?

Do you see the hotkey listed for ENTER SETUP? Perhaps F2. Depends on the manufacturer.