What make and model of PC do you have. There should be some option in the start menu to do this. Alternatively download an ISO copy of a windows XP disk that you can use to restore the PC. This is not illegal as you legitimately own a key for windows and are making a back up to restore your computer with.
ones pc is working fine thankyou!!!! i didnt reply because i turned my pc off and went to supply food to my children like a good mother should. i expect after my re formatte, to install all my programs back on my pc and be rid of all the junk that was on here, is that ok????