If you have forgotten or lost your Windows Admin password have no fear, just follow the steps below.

1. Log into a limited account and in command prompt run the following. This will copy CMD.exe in place of the login screen, so when XP reboots it will present you with a command prompt window with full access admin.

cd \windows\system32
mkdir tempfolder
copy logon.scr tempfolder\logon.scr
copy cmd.exe tempfolder\cmd.exe
del logon.scr
rename cmd.exe logon.scr
exit

2. Once you have rebooted the machine, you will prompted with the command prompt window and logged in. Use the following command to reset your admin in here (CMD after reboot) you can change your forgotten/lost password,

net user [admin username] password

3. Then copy the 2 files from tempfolder back into the system32 directory.

copy \windows\system32\tempfolder\* \windows\system32