How to change the batteries?
See out instructions here for this process: 

How long will the LED lights and batteries last?

Our Mellody Mates pillow encases 12 LED light bulbs stationed on a satin sheet inside the cushion. The LED light bulbs have a useful life of up to 50,000 hours. The benefits of LEDs are they use much less electricity than other bulbs, have extremely long useful lives, produce very little heat, do not emit UV or infrared, contain no mercury and are resistant to shock and vibration. The batteries should last between 40-80 hours depending on the quality of the brand being used.What is a Melody Mate made of?
The inside pillow filling: 100% polyester fiber
The blanket: coral fleece
The outer skin of the pillow: micro velboa (soft plush material )
The inside cushion skin material is: taffetaWhat are the washing instructions?
Unzip the outer cover and remove. Hand/Machine wash outer cover only with warm or cold water on a gently cycle and tumble dry. Check to make sure nothing is left inside cover.
DO NOT Wash or Dismantle the inner cover with components.Trouble Shooting
1. If music and lights are not turning on, be sure the on/off swithc onthe battery compartment is in the “on” position.
2. Replace old batteries.
3. Be sure the batteries are inserted correctly and location the a dark enough setting to be able to see the lights.