Last year, on my taxes I screwed up BIG TIME, and filed my unearned income (unemployment), quite by accident, under my home based, cash-earned income. I subsequently received a letter stating that as a result of this I now owed them 1800$.
I lost my 20 year old son right before I got that letter, and needless to say, I spent 6 horrific, painful months in bed. I still have the letter, but I can't find ANY of my tax stuff... only the old return. I'm in DEEP, aren't I? And, if I can even amend the return now, how should I do this?

My mom was in a similar situation, however it was due to bank errors: One was an investment company wide problem. The other two involved the bank not using the right code for bonds and mom failed to give me the statement and an account was left out of the income total.

I lost my father that year.

If I remember right, the IRS gave you all the paperwork necessary to fix the problem. They pointed out the line and the issue and if you agreed, you were done.

If you didn't agree, then there was some 1:1 correspondence until it was done.

I don't think we had to file a 1040x.

I'm sorry for your loss. Been there. Done that.

Call IRS to get transcripts of your 2007 tax return.
If you did not receive any other letter from IRS, it may be that you do not owe any taxes.
If needed, you can amend your tax return.