My realtor changed date of expiration of our contract to sell our home and forged my intials next to changed date. Can I get contract voided?

There are more issues here.  One, what are your damages?  Maybe zero.  Two, the realator will claim you consented to the initials.  What is your proof?  Finally, you cannot just void the contract without consequence.  The contract will say what happens if the date change was not made.  Maybe you would have been in default.