Windows 7: Help please, changed permissions and locked myself out

Hi,
I am a newbe to this level of computing but here goes;
I have changed the security settings of my C drive and cant access any of the windows actions. backup, restore, copy etc.My C drive wont open. I can write to the drive from word to desktop etc and can access my second drive perfectly well.
What I did was try to prevent the kids getting to my files by going to C ...right click properties...go to security tag....and change the permissions...this looked complicated and dangerous once I started and I thought I had reset it to the original settings. Obviously I had not done so and neither my kids screen nor mine as administrator can access the changes anymore. The security tab for C reports "to continue you must be an administrator etc". Pressing the continue button leaves a message "Cant open access control editor. Access is denied" Then there is no where to go. Can files be reset using any of the above?

I think you are going to have to unlock the built-in emergency Admin account.

Built-in Administrator Account - Enable or Disable There are three methods to activate.

Once you enable the hidden administrator account, restore your system using a restore point previous to the changed settings.

I suggest you create a standard user account for the kids (and anyone else) and password protect your administrator account. When you have your system back operational, disable the hidden administrator account.

Thanks..I tried that and system restore fails with Details "shadow copy provider had error.Check system log 0X80042306". When i tried that it returns "Access Denied"

Any other ideas?

can you simply change the permissions from the admin account you enabled?

No I cant change permissions from any of my user accounts for the C drive. Not even the newly set one.

I can/could for my second drive K so I can see where I made the mistake by looking at the K but when I go back to C it is now hidden completely. Can I change permissions in the registry?

Hate to tell you, but you're done. You can fight this for days, or you can reinstall Windows in under an hour. You'll never get the permissions back the way they are supposed to be regardless.

Probably, if you knew exactly what keys to go to and exactly how to configure them. But that does bring up an idea. Do you have a registry back up prior to the change? If so, restore the registry using that backup.

If you cannot do this, it is time to reinstall.

I've been searching for 20 minutes and I can't a way to change it with regedit. If there are important files you need which you can move to the K drive, I would look into making an Ubuntu live CD/DVD. As that page mentions, you can sometimes use a USB flash drive instead of a disc, but not all flash drives support it. The live CD is an operating system ran from a CD. You can't make any permanent changes to the Ubuntu OS, but you will have access to both hard drives.

Thanks,CarlTR6, Petey7 and MacGyvr...I'm done and reinstalling. Thank you all...wont make that mistake again.
Cheers all.