How do I completely reinstall EVERYTHING from SCRATCH?

I cannot load my OS, so I can't manually delete the C drive.
I press "F10" to go into the setup before the OS loads, now what?

the best I think to do this is to have your bootdisks and get to re-install from there

If you want to completly start over i would suggest you dont if there is no MAJOR problem.
But if theres no other choices you can get a boot disk to start in dos. From there type in Format C: and then wait for it to format.
After this restart, reinstall your operating system and then when thats done, you should be fine.

oh um...
this works on XP and 98 for all i know

Yes. I want to completely start over.

Problem is, I have a CD instead of a floppy.

CD works too, just make sure that your BIOS is set to accept the CD too

the windows xp disk should automatically prompt the cd..

Think this is what you mean???? if not I don't know

Step 1) Reset your computer, press del, which brings you into Bios options (Usually). I'm not sure which tab, but for me its always been the second one... under that, you can set the "Boot from" Order. Using that you should set your first boot device to the CD.

Step 2) If you have 2k, which if you don't you must burn, you should format ALL your drives to ensure a complete crushing of your problem ✅. At this point, format all of your drives into whatever partitions you want. Generally, your game drive and your "Hardware" Drive should be seperated (I.E. C, D). Format them (Usually NTFS is best). ONce all are formatted into the desired partitions, choose your C-Drive and begin your installation process.