Reset Folder Security

We have a person that had the only full access to a folder, when this person left, he deleted his a/c and now when we try to access the folders, some says “account unknown” and some just gives us “access is denied” when trying to get into the permissions tab of the folder.

How can the domain admins reset and access these folders and apply new permissions? The ones that shows “account unknown” we are able to just add new users but those other folders that give us “access is denied” – how canwe reset this if we can’t even get to the permissions page?

Thanks.