Well, there's no easy answer to this situation........
Unfortunately, losing money is no excuse for not filing your returns.
What makes you think you were losing money?
If you are losing money, how are you supporting yourself & your granddaughter? Did you receive any other earned income from a job during this period, that would have produced enough income to provide your support?
These are the kind of questions the IRS will ask you.
If you have your receipts numbers from the sales tax returns, perhaps you can identify enough expenses to more than cover the receipts & that would be one way to demonstrate that you were losing money.
The IRS would tell you to obtain duplicate bank statements & use them to figure out your income & expenses & get your tax returns filed.
Generally, in situations like this, we would start by completing the returns for the last 3 years, & then see where you stand to determine what to do next.
It is much better to get this done before the IRS decides to audit. There's a good chance that they won't come looking for you, and even if you file the last three year's returns, depending on what they show, they won't come looking for you then either.