Is there no agreed upon closing date in your contract? If not, why?
What are you requesting the extension for? The closing - or for inspection issues? If it is for the closing, how do you know what you are extending when there is no closing date?
Do you have any real estate agents and/or attorneys involved? It doesn't sound like you do - otherwise it likely wouldn't be the mess that it is with seemingly zero communication/coordination between the two parties.
Typically, if the seller is refusing to communicate a closing, and/or grant you an extension for whatever you are requesting it for - you can simply walk away and recoup any earnest money or deposits you gave the seller initially (if this even occured). You can't "force" a seller to sign over the property, if at the end of the day they don't want or are too disorganized to do so.
That said, I have no idea what the details of your transaction are - but it seems like there is no one involved to "quarterback" the situation. I would contact an attorney ASAP to either help enforce the terms of the contract, and/or communicate your demands appropriately to the seller.