If you have no reportable income for the entire tax year, there's nothing to report and no need to file. Understand that reportable income is not just earned income reported to you on a W-2 either. Interest from a bank account is reportable, as well as earnings on any investments you may have sold, among other things.
The great American tax system has become so convoluted that a simple question, like that, no longer has a simple answer.
Does "didn't work all year long" mean you didn't work at all or you only worked some of the year? Do you have children? Are you a full time student? Do you need to apply for a health insurance subsidy?
No I didn't work all year. Yes I have 3 kids. No I don't go to school. No I don't need health insurance
How do support yourself and the children? If you live with another adult, they may be able to claim all of you.
You are not required to file. This assumes you have no other reportable income. And there's no benefit to filing. The money you hear about people getting for just filing a tax return claiming kids requires you to have some earned income (wages or self employment). Without earned income, you are not eligible for the "refundable" Earned Income Credit or Additional Child Tax Credit.
For tax purposes, a child is the "Qualifying Child" of any close relative he lives with, not just his parent. For example, if you and your children live with your parents, you can allow them to claim your child, instead of you.
If you were a student, over age 23, and are not claimed as a dependent by someone else (e.g. your parent) you may be eligible for the up to $1000 refundable American Opportunity (tuition) Credit. That credit is not dependent on having either kids or earned income. You must be at least a half time undergraduate student and actually paid tuition (not just had it paid by grants). Tuition paid by loans counts as paid by you (since you have to pay that back, someday)