Filing a tax return is based on if you have a tax liability and taxable income or not. If you do not have taxable income, or a tax liability, then you do not need to file a return.
If you filed a return and the numbers on it are incorrect, you do need to Amend Your Return.
If you did not file previous years, then it is not amending it is simply filing. You would need to use download the past year programs to file. You are correct, you cannot efile, you would need to print and mail the returns. Again, if you have a tax liability, if you do not file, you will continue to accrue interest and penalties the longer you wait. An unfiled return or a fraudulent return has no statute of limitations so it is best to file.