I restarted my PC to see "Boot.ini error" ..can't load up Windows. I try to pop my disk in and reinstall, but it says I have no hard drive... 'eh? Any ideas?

First item? Check drive is still being seen/detected etc. in bios settings? Anything untoward happen prior to this problem arriving?

Well, I think it has ever recognized my hard-drive (windows setup) ...Because when my system was working and I tried a reinstall (for little reasons) windows setup in dos would give me the blue error screen. I have no clue what could have caused this, just restarted and it was there... Anyway to edit the boot.ini or get around this?

XP isn't installed via dos; which may explain the blue-screen errors... It's either via a standard CD boot or the 6 floppies + CD. Depending on how the system was configured/set-up (OS installed etc.) you may/may not see the on-screen text info that lists all drives detected/installed on this system. Some big-name outfits hide this info.; home installed systems usually don't... When the system boots up initially there is (should be) a message telling you which key(s) to press to enter the bios area (aka setup). Once in there navigate your way to current settings or whatever it's called for that bios. Drives detected will (should) be listed there. Exit (without saving any changes if in doubt) once you have had a browse... Is you XP CD a recovery or full version? Usually(?) XP systems when booted with the CD present/installed allow you the option to boot from the CD or not. Either way you are possibly looking for a repair routine - provided you do have access to the hard-drive to start with (i.e. it is actually detected etc.).