There's a very good questionnaire at www.EclecticEnergies.com, that can give you an indication of which chakra/s could use strengthening.
You can also have someone test you with a pendulum - any object hung on a string or chain that is able to swing freely. It works by responding to micro-muscular movements of the fingers, which are themselves responding to a focused question that you ask about something... you can choose what meaning to give to the following kinds of responses, e.g., clockwise circle - open chakra; counter-clockwise circle - closed chakra. I have also experienced a perfectly still pendulum when a chakra is closed. There's more info on how I use the pendulum in the prologue to The Chakra Diaries.
If you're unsure which chakra to focus on, do a Chakra Meditation to balance all your chakras, starting at the root chakra, the base for all our security and balance in life. Try the guided visualization on the Meditations page of my website www.TheChakras.org.