I am writing to inquire about the status of my federal tax refund, which was approved in April but has not been received as of today, just received the state refund.

[murillomaciel]

 I understand that processing times may vary, but I expected to have received the refund by now. I have been diligent in checking my bank account and mailbox, but unfortunately, I have not seen any sign of the refund. What do I should do?

[DoninGA]

What is the status of the federal tax refund on the IRS website?

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.  

If accepted by the IRS use the federal tax refund website to check the refund status - https://www.irs.gov/refunds

After the tax return has been Accepted by the IRS (meaning only that they received the return) it will be in the Processing mode until the tax refund has been Approved and then an Issue Date will be available on the IRS website.
See this IRS website for federal tax refund FAQ's - https://www.irs.gov/refunds/tax-season-refund-frequently-asked-questions

Call the IRS: 1-800-829-1040 hours 7 AM - 7 PM local time Monday-Friday
When calling the IRS do NOT choose the first option re: "Refund", or it will send you to an automated phone line.
So after first choosing your language, then do NOT choose Option 1 (refund info). Choose option 2 for "personal income tax" instead.
Then press 1 for "form, tax history, or payment".
Then press 3 "for all other questions."
Then press 2 "for all other questions."
- When it asks you to enter your SSN or EIN to access your account information, don't enter anything.
- After it asks twice, you will get another menu.

Press 2 for personal or individual tax questions.
Then press 3 for all other inquiries
It should then transfer you to an agent.