visual style BIG PROBLEM

hey guys i really need help in this.. my visual style doesnt change.. it suddenly became into windows classic and now i cant change it.. can u help me in this please.. when i try to change it an error messege apears and says "The theme could not be loaded because the theme service is not running. You can turn it on in the Computer Management Administrative Tool in the Control Panel" .... so i went there and checked the theme service it was on and working.. i refreshed it and restrated it.. but nothing changed .. it still gives me the same ANSWER !! .. its really important to me guys please.. help me in this and thx ^^

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Dude no.. u didnt understand my problem.. thx for trying to help anyway
its about the theme .. when u right click the desktop and then properties .. and then when u wana change the theme or visual style.. k, u press on any theme u want and it changes .. but with me it doesnt it stays in windows classic and the error messge apears .. the one i hav just mentioned above
i hope somebody could understand it :31: .. read carefully people, and thx