First of all, if you filed a tax return in 2018, you don't need to file one in 2019 to get your stimulus check.
What income was the form 1099 reporting? What was the form number (1099-DIV, 1099-INT, 1099-B?) and how much was the income on it? You may not have to file a tax return for 2019, in which case you can just register for the stimulus check.