What happens if the police failed to read me my rights?

If you were taken into custody or deprived of freedom in a significant way, you are entitled to have your rights read to you, including the right to remain silent and the right to have an attorney present. If your rights were not read in such a situation, then any information that you gave during the subsequent questioning cannot be used against you. In addition, if information that was obtained during that interrogation led the officers to discover further information, the subsequent "fruit of the poisonous tree" is also not admissible as evidence to prove your guilt.