Windows 7: Take ownership help please to reverse this

I have been very silly and used info from the web to solve an installing )Office 2013 which had a 1603 error How can I reverse this my machine will not load now,,even in safe mode..help takeown /f C:\Windows cacls C:\Windows /G administrators:F all permission seem to be screwed up HELP please

I don't know if this will work, but see option 2 in this tutorial. System Restore

essenbe Thanks for the reply..i am on my 6th system restore each different..not even sure if a restore would include the registry of the day created

You will have to pick a restore point to before you took ownership.

Read these tutorials and see if there is some information that will help you.
TrustedInstaller - Restore as Owner
Read the tip at the bottom of the page
Take Ownership Shortcut

Sadly I think I have taken ownership 0f the C;drive..can it be undone,,

Truthfully, I don't know if you can't boot into Windows at all. If you can maybe the first Tutorial I linked to will do it. If not you could try a Repair Install. If that does not work, you may need to clean install. I am not familar with your computer brand, but most have a tools partition to return it to factory state, although most people prefer the clean install to rid themselves of the factory bloatware. Clean Reinstall - Factory OEM Windows 7
If you need to get your personal data off first, which I recommend no matter which method you use, you will need an external hard drive or some place to put them and Copy & Paste - in Windows Recovery Console

If you have any questions, please feel free to ask.

I have asked our resident expert to take a look. He may have some ideas I don't know.

Have you tried booting into the Windows 7 DVD or System Repair Disk to run Startup Repair a few times? This should automate all of the fixes including System Restore which is also best run from the disk since OS files may have been corrupted.

Next try SFC /SCANNOW Run in Command Prompt at Boot

Next try Built-in Administrator - Enable from WinRE - Windows 7 Forums to see if it will boot.

If not everything else that can be done is in Troubleshooting Windows 7 Failure to Start
leading up to rescuiing your files if necessary to run factory Recovery or get a perfect Clean Reinstall
which after setup you can image to use in place of future reinstalls.

Its so frustrating. It was a stupid thing to do I am now using Hirens 15.20 and on there is a windows xp mini boot etc..II can see all my hard drive which have most of my data If i import a full Jan 2013 registry will it replace or merge with current corrupt one..Can I remove the corrupt registry first and then using regedit import and to where. I have just bought windows 8 pro and was wondering if i can use that at all ....would it wipe out the registry as it is now..HELP I cannot boot from C in any way,,not even safe mode so I cannot get to the command prompt unless you caN TEACH ME HOW.. the mini xp seems to be limited. I was hoping I could remove all the permissions etc or at least get it to boot

You can get to a command prompt from the installation DVD. There are 2 ways.
1. Boot from the DVD, on the first window, do not select your language, hold down shift and press F10, it will bring up a command prompt window.
2. On either the 2nd or third screen when booting from the DVD, in the bottom left it says repair my computer. you can click there and it will do startup repair, which I would try. or click through to other options and one will be a command prompt.
From what little I know about the registry, importing a clean registry will not fix your problem. You have software installed which write registry keys, and they will not be changed. Merging a new registry will only change the keys included on the DVD and not all of the ones you have changed. You would have needed to do a registry backup before you took ownership.
Your best bet would be to do a system restore from the DVD or try the startup repair from the DVD.

Personally, if it were me, I would do the startup repair and system restore from the dvd. If those did not work I would try a repair install. If that didn't work, do a clean install. The time you have already spent, you could have done the clean install and have a working computer. Use the Hirens to get your personal files out first and try the repair from the installation DVD. If you do the registry change, you will only change the keys that are on the DVD. Any keys or values that were changed will not be affected. What I honestly believe is that if you manage to fix it to where you can boot, you will still have a problem install. You can spend more time trying to fix something than it would take to do a clean install and be done with it and have a perfect install. That's my personal opinion based on numerous hours trying to fix something I have messed up. Don't feel bad, most of us have done the same type stuff and worse. But, we learned a lot about things from the experience. If the steps Greg linked to on troubleshooting Windows 7 don't work, a clean install is your only option, I believe.

EDIT: I am far from an expert on Windows registry. I am only telling you my opinions.