No sound in Windows 7 but works in linux

My daughter recently installed Win7 to dual boot on her Linux machine. All’s well except there is no sound when in Windows. All indications from Windows is that the sound is working but no sound comes from speakers. Even the VU meter in the volume slider indicates sound is working. When she moves to Linus, sound works perfectly. Someone please help me so I don’t have to suffer the wrath of the Little Linux Nazi.