When will I receive my state tax? It's been past 21 days.

Make sure your state return was accepted:  https://turbotax.intuit.com/tax-tools/efile-status-lookup/

Federal and state refunds come from completely separate entities.  You cannot expect them to arrive at the same time.

To track your state refund:    

https://ttlc.intuit.com/questions/1899433-how-do-i-track-my-state-refund

Did you e-file your state tax return and was it accepted?

There is no set time period for when the state tax refund will be Issued.
Only the IRS and your State control when and if a Federal or State tax refund is Approved and Issued.

You complete your tax return by finishing all 3 Steps in the File section. In Step 3, to e-file your tax return, you must click on the large Orange button labeled "Transmit my returns now".

After completing the File section and e-filing your tax return you will receive two emails from TurboTax. The first email when your tax return was transmitted and the second email when the tax return has either been accepted or rejected.

Note - Once a tax return has been Accepted by the IRS or a State, TurboTax receives no further information concerning the tax return or the status of any tax refund.  Only the taxpayer listed on the tax return can obtain the status of a tax refund or a tax return.

Use this TurboTax website to check the status of an e-filed return and if it was either accepted or rejected - https://turbotax.intuit.com/tax-tools/efile-status-lookup/

If accepted by the state use this TurboTax support FAQ to check the state tax refund status - https://ttlc.intuit.com/questions/1899433-how-do-i-track-my-state-refund

many states take longer than 21 days to make a refund.   21 days is just an IRS goal, but even with them it sometimes takes longer