Depending on where in the world you are the Ubuntu web site should be offering the 22.04 download. Here is the page for 22.04 downloads directly: https://releases.ubuntu.com/22.04/
If not, here is the link to the (AMD 64 Desktop) .iso directly: https://releases.ubuntu.com/22.04/ubuntu-22.04-desktop-amd64.iso
If you're running 20.04 or 21.10 you can upgrade in place: https://www.omgubuntu.co.uk/2022/04/how-to-upgrade-to-ubuntu-22-04-lts
If not, here is the link to the (AMD 64 Desktop) .iso directly: https://releases.ubuntu.com/22.04/ubuntu-22.04-desktop-amd64.iso
If you're running 20.04 or 21.10 you can upgrade in place: https://www.omgubuntu.co.uk/2022/04/how-to-upgrade-to-ubuntu-22-04-lts