I accidentially cancelled the User ID: Administrator on my computer which runs Windows XP, now I cannot start up anymore. How to recover ? How to skip this step of asking for Administrator password every time I start the computer ? Thank you.

Did you have any other account on the computer?

Usually the administrator account is only used in safe mode.

If you can't fix the problem, back up and restore is a viable option.

I have deleted all accounts on my computer. The administrator account used to pop up every time when I turned on the computer. That's why I tried to remove it.

You are far too stupid to own a computer.. take it back to the best buy where you bought it and ask for a 'Pity Return'