There are a number of things you can do to help thinning hair grow back. First, it's important to understand the cause of your hair loss. If it's due to genetic factors, there's not much you can do to change that. However, if it's due to stress or other lifestyle factors, there are things you can do to improve the situation.
getting regular massages, which can help improve circulation and promote hair growth
taking supplements like biotin and fish oil, which are known to support healthy hair growth
using essential oils like rosemary and lavender in your shampoo or conditioner, which can stimulate hair growth