KIndly reboot your server and try again,
if that dosnt work run this command
sudo apt-get update && apt-get upgrade -y

that should fix it

if not then read your error logs for a more detailed issue

Hello,

Did the reboot, suggested by @thousifme18 solve your problem? If not, here are some ideas:

• Kindly note that usually URL is case sensitive. Ie. PhpMyAdmin folder’s name is phpMyAdmin but you are trying to access example.com/phpmyadmin

Firewall

• Check *port 80 * on Firewall

  sudo iptables -A INPUT -p tcp --dport 80 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
  sudo iptables -A OUTPUT -p tcp --sport 80 -m conntrack --ctstate ESTABLISHED -j ACCEPT
  

• Check if *port 3306 * inbound allowed on Firewall

sudo iptables -A INPUT -i eth1 -p tcp --dport 3306 -m conntrack --ctstate NEW,ESTABLISHED -j ACCEPT
sudo iptables -A OUTPUT -o eth1 -p tcp --sport 3306 -m conntrack --ctstate ESTABLISHED -j ACCEPT

More info available at https://www.digitalocean.com/community/tutorials/iptables-essentials-common-firewall-rules-and-commands

phpMyAdmin Config

• Check your config file. If it doesn’t exist, you can create one

Felipe