Who are "they" who said to look at your 2013 tax return, and why are "they" asking now, 12 years later? You would not have reported an inheritance on your tax return. An inheritance is not taxable income, and is not reported on your tax return. So even if you could look at your 2013 tax return, and you did get an inheritance, the inheritance would not be on the tax return.
A tax professional can probably get a transcript of your 2013 tax return from the IRS, with your permission. A transcript lists the information from your tax return, but it is not an actual copy. It is not in the format of the actual forms. The IRS does save transcripts longer than 7 years.
