I mailed my return on April 16 why haven’t I got my refund yet

[mesquitebean]

Did you print, sign, date, and mail your return?  TurboTax does not mail it for you.

So assuming you physically mailed it, be aware that the IRS has not been processing paper returns the last several weeks due to Coronavirus situation.   Paper returns have been stockpiled in bins and trailers.   They may have started processing some now, but there will be a huge backlog.   The IRS says NOT to file a second return.

All you can do at this point is to keep watching this IRS "Where's My Refund" tool occasionally, such as 2-3 times a week.  At some point, it should (hopefully) show up in their system when it is logged in and processing begins.

https://www.irs.gov/refunds

When using the IRS WMR tool, be sure you enter the correct SSN and filing status.

Use only the Federal refund amount.  Do not use any combined total refund figure that includes the state refund.

Look at your actual 2019 return to get the Federal refund amount.  Be sure you are using what is displayed on your Federal Form 1040, Line 21a for the Federal refund amount.

[mesquitebean]

And did you also have a state return?    If so, hopefully you mailed the Federal return to the IRS and the state return to the state tax agency.   We have seen some people incorrectly mail both of them to the state tax agency before and nothing to the IRS, or vice versa. 

FAQ:  How do I track my state refund?

https://ttlc.intuit.com/community/refund-status/help/how-do-i-track-my-state-refund/00/25571