Database dissapeared

Hello to all,
an amateur from here asking for some kind of help
my history
yesterday, installed everthing, all running ok, added lots of content
get some sleep after all of this
this morning, ready to start working again and i get this:
“Error establishing a database connection”
ok…i thought… i’m done :\
Remembered to login into PHPAdmin to check databasem yesterday i saw it was there…today nothing appears there.
ok…
i decided to login via FTP and read the config file…all info there are according with the info i get from my host, not changes.

Now, i dont what to do. Because im cautious about this stuff i’ve installed this plugin
“http://wordpress.org/support/view/plugin-reviews/wponlinebackup”
and it worked, this morning i had in my inbox email the backup of the file
but now…what is supposed to do if i cant even get a login in wordpress?

:\