Please... I have no clue about mysql. Can someone please help?

Push the link above to see what I mean

Is your database running?

Do you have access to command line on your server?

If yes - try sudo service mysql status if the status is active or running. If not, try the same command but with "restart" instead of "status".

If it's running, try to log in to the database using the credentials you have created for your user.

I suppose either the database is not running, or the password is wrong, or you have no such user.

It would be helpful to know how you set up your ownCloud