The IRS only handles federal tax returns, not state tax returns.
If your state contacted you by mail you should call your state tax authority to verify the letter you received and to also verify what they need from you, if anything.
See this TurboTax support FAQ for contact a state department of revenue - https://ttlc.intuit.com/turbotax-support/en-us/help-article/state-taxes/contact-state-department-rev...
TurboTax does not support tax year 2015. If you are required to file the 2015 state tax return you will need to find a local tax professional to assist you in completing the state tax return.
