The process of unblocking your chakras is not one that is completed in a short time. But improvements can be made quite quickly. It's a process of self improvement over the course of your entire lifetime, and it is extremely rare for a mind/body/spirit complex to ever be completely balance with fully open and free flowing energy centers.
Each person is different, therefore the process of unblocking and balancing your chakras is unique to you. It first requires exploration and knowledge of the self, that's the totality of all energy centres, before each can be unblocked. An example might be a blockage in the green chakra resulting is an inability to express love. Exploration and careful contemplation of the self is required in order to understand to what extent the person feels is a balanced amount of love. Once this balance is found, then for example, the orange chakra too will begin to permit more free flowing energy due to a greater acceptance of the self. By balancing one chakra another becomes more balanced.
Meditation and contemplation are required on the concept of the self. Yoga too will help. Think about who you are and what you consider to be balanced. Self discovery helps to balance chakras, and then the correct levels of positive or negative energies can flow. Remember even a negatively orientated person can balance their energies, if they are mean through and through, then they can find negative balance!