What to do when Windows XP won't boot?

When my computer tries to boot up, the Windows XP loading screen comes up for a second and then disappears and goes back to the screen with all the options such as "safe mode" "start windows normally" etc. Help! This came on suddenly. I didn't install any new software or anything at all... I need to access that computer because all of my summer reading homework is on there :( I was too stupid to save it to a flashdrive. Please please please help me! We tried all the safe mode stuff and that didn't seem to work either. We checked the chords and made sure everything was plugged in and everything. I don't know why this is happening D: