I assume yu have been provided the services of a Public Defender to defend you in criminal court. If not, request the court to appoint you counsel ASAP.
The prosecutor can "change the theory" of the case prosecution to adapt to the facts. But he has to convict you by evidence beyond a reasonable doubt to a jury of 12, if a felony offense. The prosecutor must follow the elements of the crime charged to win a conviction. The prosecutor can amended, dismiss and/or add charges if allowed by the court in your jurisdiction by a new criminal complaint or a new indictment.
You are entitled to a copy of your file, it is public record. Go to the clerk's office or ask your PD to get a copy for you.
I am trying to give you a general answer to your question. We do not have an attorney-client relationship by this response on the avvo website. I have not been retained to represent you. I am licensed to practice law in Kentucky and in federal court in this state and the Southern District of Indiana. You need to seek legal advice from an attorney licensed to practice in your area..