Minecraft world does not appear?

I copied the Minecraft folder from my old laptop and transferred it to my new laptop with the USB stick. I logged in and then the 1.14 update was first uploaded. I wanted to play and when I clicked on singleplayer, all my worlds were gone.

Why is that and how can I get my worlds back?

Make% APPDATA% in the search bar and open the Minecraft folder there. In this is a save folder. Copy your worlds from the stick in there and they should be displayed in the singleplayer.

If not, reinstall Minecraft and then copy the worlds.