Lost Database Connection after password change

Hi my website was running fine on a free hosting site (I’m new to WP and am trying it out) – Before upgrading to 3.8 I was trying to back-up the database then opted to Change Password (don’t ask why as I have no idea!) which i did but now the website URL is only displaying the ‘Error establishing a database connection’.
I’m not sure what the original password was now, I tried to use the one in the wp-config file but was told i couldn’t use it as it wasn’t in the correct format.
I can access the file manager, FTP, MySql and phpadmin.
I just don’t know what to do! The support for the hosting site is on Christmas holidays. I am trying to build a website for a charity that we were planning to launch in the New year. Can anyone point me in the right direction please. Thank you!