What can I do if I have lost W9 and 1099 forms for 2016 I haven't filed in a few years because of this issue?

Luckily, you don't need copies of your 1099s to file your taxes because you aren't required to submit copies with your tax return, like you are required to do for a W-2. If you use accounting software to track your business income and expenses, you can use the profit and loss statement to find out how much income you earned. But if you don't use accounting software, you can look at your bank statements from 2016 to find out how much you earned. You can also call anyone that would have sent you a 1099 in 2016 and ask if they can send you a duplicate.