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When playing with the controls on the start up of my PC I somehow managed to lose my administrator and now can only use my PC as a second user. I have no idea what my administrator pass word is so am unable to sign in and get it back to how it was. I can not even run things like the disc defrag and put new programs on so it will only be a matter of time before I run to a grinding halt. Any help on how to basically install a new administrator or how to get the password would be great. This is a second hand PC and sadly I do not have many of the installation discs that I hope I do not need.

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marked as duplicate by Ƭᴇcʜιᴇ007, 8088, Mokubai, Dave M, Scott Mar 16 '13 at 0:03

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

I would just reinstall Windows XP. Extract the authenticatin key for your installation using te current account that works. – Ramhound Mar 15 '13 at 17:37

Since you have physical access to the machine you could always pop in a Live CD like Ultimate Boot CD or follow this guide and reset the password. DO NOT ATTEMPT this though if you have selected the "protect user data" option on account creation as that has turned on encryption and all your user data will be inaccessible after resetting the password.

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if using the ultimate boot cd the utility you will need is under /HDD/Data Recovery/Offline NT Password & Registry Editor I believe... it's been a while thought ;p – hwshadow Mar 15 '13 at 15:49

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