Windows 7: permission denied drice c

All,

i have the following problem:

I wanted to "decrease" the permission to one of the hard drives.
By mistake I have denied the permission to my system hard drive c and i cant acces it now.

I cant access it from the admin account , i cant change security settings ,

I have the message acces denied or i dont have enough permission to do so even if i am using the Admin account

anybody did have the same problem

please help

rdgs

paul