Start with this video from Legacy Film Lab to figure out the cause and solution for your blank roll.
Why did my roll come out blank?
The most common reason for a blank roll is a camera loading error. This occurs when the film leader is not fully attached to the take-up spool, and so the film never advances. It can also be due to a camera problem, like dead batteries, a broken light meter, incorrect settings, or a mechanical problem with the shutter or film transport. When a roll comes out blank, we send a store credit for the cost of scanning ($3 for basic scans, $8 for premium, $13 for pro). You will also receive a credit for the cost of printing if you ordered prints. If you got a blank roll, feel free to bring your camera by any time and we can go over what went wrong and how to avoid it in the future.
Why don't I get a full refund?
We have to develop the film in order to determine if there are photos on it. This is a labor intensive process which consumes energy and materials. It costs us the same to develop a roll regardless of the number of pictures it contains. When a roll is blank, we can skip the scanning (digitizing) portion of the order and so we issue a refund for the cost of scanning.