You cannot edit a certificate. I suggest that you generate one using Letsencrypt

https://www.digitalocean.com/community/tutorials/how-to-secure-apache-with-let-s-encrypt-on-ubuntu-16-04

Looks like you are using self-issued certificate instead of GoDaddys one.
If you look at Issuer field at SSLabs, you will notice your host name - Self-issued.

Make sure you followed right tutorial to download cert from GoDaddy.

Tutorial you linked is right one, I would recommend you trying again to obtain cert. Follow Example CA 2 : GoDaddy again.

Also verify in GoDaddy panel that you entered right domain, but I don’t that it is problem.

Thanks for the reply @xMudrii , this time I have created a new droplet and re assigned the CSR,
even then I am not able to get the website up and running with ssl. the moment I configure 000-default.conf the website goes down.

The certificate does not match the private key -is the error I get when testing - but how can a key mismatch when it was generated through the server?

It has been 24 hours - I am just banging my heads on this!!!

One question is it necessary to have a sudo user? As I am only doing as a root user.

Please help.

Ok got it solved. thanks for all the help