After you file

I filed my taxes thru turbo tax as of Jan.28th 2020..I did recieve my state refund within that week of filing and plus was approved for a 1000 dollar federal tax refund advance and got that the same time I recieved my state refund..But its 4-15-2020 And still no federal tax refund did however recieve a letter 3-12-2020 saying it's on a 60 day hold and if they needed amything from me they would mail me another letter..I reviewed all the information in my refund and it is all corect..Not to mention never recieved my stimulus check today...What seems to be the problem??