hello alll i have a dell c400 with no floppy or dvd rom, but i do have a external dvd rom drive. no thing is i need to re-install windows xp but it cannot find the drive even when i hit f12 is they anything i can do before i take down my local computer repair shop

On that computer in order for it to boot to the external Cd it must be connected to the external IED port on the left side of the case. It does not support booting from USB if i remember right. get a matching USB adapter for the IED port and connect it to the USB of the external drive and that will allow you to boot to that device.

Try this, when you boot up your computer, after a few seconds, you will see a blue line across the top of your screen, it will say something about dell. As soon as this line comes up, tap the Ctrl key and the F11 key at the same time, this should bring up the built in option to restore the computer to like new condition. Just follow the prompts and you should be ok, no need for CD drive.
Good Luck

That laptop came with restore discs and not a restore partition.