SPC and Ammending tax returns

Thanks for having this amazing forum available!  I've got some questions about taxes.  I'm securing my SPC status over the next couple months and have some questions about past year taxes...  I haven't filed for two years now and haven't had a significant income, though likely taxable if I looked at the numbers.  Four years ago I was divorced and filed separately for the job I had, then went on unemployment for a year and didn't pay taxes on any of that money. So, now that I am correcting my SS application can I file amended forms for previous years to correct my tax status from those dates, thereby creating a zero tax owed and get a 100% tax refund?   Should I even bother filing tax forms on those previous years that I've neglected and start again this year with the proper forms for my current status? How do I go about reclaiming the years of social security payments I've made?  Is that all just water under the bridge? I appreciate your guidance in this matter.