<<How can I reinstall when my computer froze after I start it up? >>
Ok from the looks of things, you may be screwed. But if you have a boot disk, thats a start if not you need access to one. Since you can get online, you've got a computer (hopely PC) that you can use to make one. Secondly see if you can load your cd drivers on the boot disk, and see if you can access your C: Drive, if all those things are good then you can install from the CD after you boot from the boot disk.
Alternatively, if windows wont boot you might want to try holding F8, right before the splash screen is supposed to come up, this should give you a option menu to start in safe/MS-DOS/Normal Mode. Go to MS-DOS and try to access you CD-ROM Drive from there. If you can't you need to load the cd drivers in your config.sys file.