Administrator of files and folders

Hello,
I have a big problem. I have vista home and I am the only one that does anything with my computer. I was trying to access a file or something and it tells me windows cannot access the specified device or file. You may not have the appropriate perrmission to access the item. I then go messing with the ownership and changed some things, well now it really is messed up. I need to know how I change it back the way it was. I don't know if I do a system restore, if it will reset what I fooled with. I guess I need to be the administrator. I know some files had my name-PC and I also seen it had adminstrators (my name-PC\administrators)