You might have grabbed the wrong iso. There are two ISOs for Ubuntu, one is desktop which comes with a desktop and the other is server which only comes with a text console.
You can install a desktop onto a server image if necessary, however I would recommend just using a desktop iso and don’t bother with adding on and setting up all the desktop software.
If you want to be able to select text, copy and paste, I just SSH from Windows Terminal or Mac iTerm2
Alternatively if it is a desktop iso then you might have accidentally installed a package that broke things or have gone a tty interface. There’s so many different possibilities it’s going to be hard to help more.