The requirement to file a tax return is based primarily on your income, not how much you owe. Being disabled and being a veteran do not affect whether or not you have to file. You can use Do I need to file a tax return? on the IRS web site to see if you have to file a federal tax return.
Each state has different filing requirements. You would have to check the requirements for the particular state that you live in and any other state where you worked or had income from. You should be able to find the filing requirements on the state's taxation web site.