Hi Tracey,
This is something you really need to work out with your supplier/s. You need to know what their warranty policy is on the products you will be selling, that will then let you know what you have to build into your policies for your customers. The important thing to remember about dropshipping is that the buyers are your customers, you are the only customer of the dropshipper. So you need to be right up to speed on warranty and all other policies of your supplier/s that can and will most likely impact on your business.