I can connect to the VPN but when i look my public IP its exactly the same as the one i had before using the VPN. What could be wrong, i use an Ubuntu server and my computer is also Ubuntu.
Did you follow one of DigitalOceans' tutorials? If not, how did you go about setting up the VPN? There is a guide that details what's needed to setup OpenVPN on Ubuntu 16.04 below:
https://www.digitalocean.com/community/tutorials/how-to-set-up-an-openvpn-server-on-ubuntu-16-04
Running over the guide on my end, everything appears to be working as it should. I would take another look over the guide and double-check the configuration to make sure all is in place as it should be. It can be easy to miss a step from time to time, especially on longer guides.
I have a test droplet running using the same guide on my end and when testing which IP is being used to connect via Google, it's showing my Droplet IP as it should.