Why wont your flat back labret go in?

If your flat back labret won't go in, it could be due to swelling or irritation in the piercing, making it difficult to insert the jewelry. Additionally, the size of the labret post might not be appropriate for your piercing, or there could be residue or crusting around the hole that is blocking the entry. It's important to ensure everything is clean and to avoid forcing the jewelry, as this could cause further irritation or injury. If the issue persists, consider consulting a professional piercer.