If your shower is fitted with individual LED lights and you find one is not working, but all the rest are? You would first need to check the connection is correct. The likelihood at this point is it is working if all the other lights are working as it's making a complete circuit, but no harm in double-checking.
Only a few lights work, the rest are all nonoperational.
The issue here is not that ALL the lights are not working, it's the fact the next light in the series is not passing on an electrical current illuminating the rest of the lights. In the first instance, check all connections are made correctly. If this doesn't solve the issue, the next step is to remove the light from the circuit by bypassing/connecting the working light to the light after the one that isn't working and see if all the other lights turn on. If this does solve the issue, then you need a replacement light.
Ordering a replacement light
If you are within your first 12 months of warranty, this part would be replaced under your policy for free. Simply create a support ticket and a member of the customer service team will arrange this for you. If you're outside of 12 months, as stated in the warranty terms, these are considered a consumable part, and as such a replacement can be purchased here.