If you cannot pay what you owe, you can request an additional 60-120 days to pay your account in full through the Online Payment Agreement application or by calling the IRS. If you need more time to pay, you can request an installment agreement or you may qualify for an offer in compromise.
File all tax returns that are due, regardless of whether or not you can pay in full. File your past due return the same way and to the same location where you would file an on-time return.
If you have received a notice, make sure to send your past due return to the location indicated on the notice you received.
It's truly amazing how fast tax penalties and interest add up. Now you have a choice, you can write a big fat check and pay the full amount, including interest and penalties. Or you can just keep ignoring them while the penalties and interest keep piling up.