Where is your agent in this?
Once the contract date has expired without a closing or having an agreement to extend the closing date, your deal is done!
To get things moving forward again, you will need to get the seller back on board with the agreement and a new closing date.
The Seller is not required to even answer you; and the way etiquite is today; I wouldn't hold my breath.
The next thing is, you will probably lose your DEPOSIT.
Not to mention losing the house.
You didn't say why you would need an extension:
It sounds like you were trying to do this without a Realtor.