Not wearing a helmet is a bad idea because it is illegal in most cases and extremely dangerous in all situations. However, you don’t lose your right to file a motorcycle accident claim just because you didn’t have a helmet on. If your crash was caused by someone else, then you can still bring a claim against them.
You can expect your liability to go up because you didn’t have a helmet, though. The more liability you have, the more difficult it becomes to get the compensation that you need.