There could be different reasons why your battery is not charging or staying charged.
In most cases, if your device has a rechargeable battery, it will come with a charging cable.
Check the charging cable to make sure it is fully connected to your device and plugged into a wall outlet. Once confirmed there should be a light on your device. If there is a light, that usually indicates that the charging cable is good.
If your device is still not charging, you may have a defective battery or your device battery has been overcharged preventing it from fully charging or charging at all.
For complete steps on charging your device, please refer to your manual which can be found on the product page for your device. You can reach the product page by searching for your model number using the search box in the upper right hand corner of the website.