1. Cancellation or specific performance of a contract depends on the fact as whether therein the time for completion of sale was made the essence of the contract.
2. So check whether there is any penal clause of cancellation clause in the sale agreement if the sale is n0t completed within the stipulated time.
3. if that is so then send a letter of cancellation, return the earnest money and enter into another agreement with another person.
4. Before cancellation a window for 15 days is advisable to be given to the buyer to complete the deal.