Why is there a delay of 4 months after taking Rigevidon pills?

Do you mean that there was no bleeding for 4 months of using Rigevidon tablets? If there is no bleeding during the 7-day intervals, pregnancy should be ruled out. To rule out pregnancy, a pregnancy test should be performed, such as:
https://www.gdziepolek.pl/produkty/97388/pink-test-ciazowy-strumieniowy-super-czuly-domowe-laboratrium-test/apteki

On our portal, after adding a product to the cart, you can compare its prices in online pharmacies and place an order with home delivery or pickup at the pharmacy. In cities such as Warsaw, Wrocław, Łódź or Białystok, products can be ordered with instant delivery even in 1 hour thanks to the Wolt Drive service - check if the service is available in your location: https://www.gdziepolek.pl/koszyk/szybka-dostawa?src=zf