Easiest way to upgrade Ubuntu 14.04 to 18.04 for a newbie?

I have Ubuntu 14.04 and Nginx for running several Wordpress and Drupal websites. I was having problems running “sudo apt-get update” and learned that 14.04 is EOL, so I’ve tried to upgrade to 18.04 following https://www.digitalocean.com/community/tutorials/how-to-upgrade-to-ubuntu-18-04, but it doesn’t work, it doesn’t find the appropriate files and it “gives up”.

I’ve read some posts and apparently is pretty frequent to encounter problems during the upgrades between versions, so it’s recommended to move to a new server. I’ve looked at https://www.digitalocean.com/community/tutorial_series/how-to-migrate-to-a-new-linux-server but it looks super complicated for me and I’m afraid I would be blocked as soon as 1 error show up (I have no DevOps knowledge, I’ve just installed everything following the DigitalOcean guides).

Maybe it’s easier to just install a new DigitalOcean image and move my files “manually”? I don’t have any custom stuff, only the things recommended by the DigitalOcean guides to install Wordpress and Drupal. So I guess just by moving the Wordpress/Drupal files and databases to the new server everything could work fine.

Also, I’m using Nginx because it was supposed to run faster than Apache, but ran into several small problems over the years (and there is always more documentation for Apache), so I was thinking of changing to Apache at the same time I upgrade to Ubuntu 18.04. Not sure if it’s a good idea or that would cause a lot of problems.

Sorry for the newbie questions and thanks for your help!