The IRS stated that they did not receive a tax return for 2003 from me and they did a substitute filling on my behalf. I cannot locate my tax return for that year and unfortunately my account has passed away. They say I owe them a preposterous amount of money what can I do?

ask your previous employer for a copy of your w-2 they keep records too. also contact any banks etc for 1099's

Surely the records from your "account" (accountant) are still stored somewhere?

Without a copy of the return that was supposedly filed, you don't have any way to defend yourself.

I suggest you contact an attorney, you are going to need professional help with this, soon.

Another option is to ask the STATE for a copy of your return. Some states (like California) require a complete copy of the return be submitted with the state return.

If, so some reason, you cannot get the W-2s and Form 1099s, and/or you cannot find the 2003 tax return, then you need to contact the IRS and get a copy of your 2003 tax script. It is free and will contain an complete paper trail of all pertinent tax documents for your federal return.

With that tax script, any competent tax professional can reproduce your return, then submit an amendment to correct the return done for you by the IRS.