Hi, Karla, are you working with a Realtor? Your agent should know how to handle this.
If a C.A.R. form RPA-CA was used and the buyer and seller properly executed the agreement, there are exactly ten reasons why a seller may cancel. "The Seller doesn't want to sell" is not one of the ten reasons!
Most buyers faced with this situation just want to be made whole by getting their deposit back along with compensation for expenses, if any, and look for another suitable home to purchase. But, it may be possible, if you wanted to buy the house and you fully perform your part of the purchase agreement, to seek "specific performance" and force the sale or seek damages; you would need to consult with your attorney about possible remedies.
I am a real estate broker qualified to advise you on California real estate matters, not the law. If you desire legal advice, consult with an attorney.
Best of luck!