Welcome to LinuxQuestions.org. Try pressing <ctrl> + <alt> F(1-6) when you boot up and get the blank screen. That will bring you to a terminal. Login as root, then go into /etc/X11 and edit your XF86Config file with the proper configuration for your monitor (it sounds like a resolution problem).
I've never tried Fedora, back on redhat days, you could call redhat-config-xfree86 from the terminal to (re)configure X display. Try doing that (typing redhat-config-xfree86) after you boot up and call a terminal (with ctrl + alt + F2, for example) as root.
If you don't have anything important on your Linux partitions, reinstall it and make sure to put the correct values for your monitor and card during the install (it does, check for X, doesn't it?).