I have a Dell studio 15 laptop that plays blu-ray discs. When i bought it, it played the discs fine. we have since played discs through the laptop onto the tv. Since then i now have no volume when i play them on the laptop but windows media player plays music fine with volume . I have obviously done something daft. If anyone can help i would be grateful. i am not very good with computers (obviously!) so please make any help as basic as possible. many thanks.