C drive access denied in Windows Vista

I am getting a strange error on my vista. When i click on my computer i see that the C drive is access denied ..I cannot do anything ..I use the explore but cannot copy / save files. When I go to the propoerties of the c drive and chk for permission i see that there is no owner defined. When i try to do an edit and select something i get access denied.. tried everything but no luck…it wont allow me go to manage computer either.

any ideas / solutions need urgent help

thx n rgds

alok