The IRS has contacted me. I need to file state taxes for the year 2005 how can I go back and do this?

The IRS has nothing to do with your state taxes.   Did the state contact you?  And---really----2005?   Or is that a typo?   And...how were you contacted?   The IRS never calls you.   Please provide some details.   Some one might be trying to scam you.

if it's really from NYS and really for 2005 (extremely doubtful but I could be wrong) here's a link to 2005 tax forms.

https://www.tax.ny.gov/forms/prvforms/income_tax_2005.htm 

do you even have the tax documents from that year? you'll either have to prepare the return manually or seek out a tax pro that has tax software dating back that far.