Administrator rights

Help, please. The day before yesterday, some garbage appeared, I can’t delete anything, copy, etc., writes ask for permission from PCUser or PCAdministrator or PCAdministrators. And I'm not a slow poke, I'm rummaging around. Che I just did not try and give full access and something else. Help me please. I have Windows 7 Home Premium, there is no local user management in computer management. It was not me who installed Windows, the master came (although I would have installed it better) HERE is such a problem. Thanks in advance =)