Has my site being hacked?

[oscuroknight]

First of I am new to this of trying of being a webmaster and my only experience is a couple of months learning as much as I can every day.

Two months ago I finished installing my site,had everything ready,Style and my hacks(post thank you) (reziser) (hide hack) (Links Redirect) (Slider)(Spam Moderation Mod)installed so I went live.
Everything worked perfect so I pay google to promote my site and I started having a few members sing up. have a couple of bots post spam and dealt with them .

A few days ago i installed Vbadvance and after I upgraded my hide hack mod I started to notice strange things to happen on my site.

First some parts of my cms page disappeared, so I went crazy doing research to find the solution to this. without success;then I notice that only the part of the grid under my slider widget was the only one that disappeared;so I try to move it to A diferent place in the grid and did the same,No matter where I moved it,that part under the grid dissapeared. so I opted to remove my slider from the grid and everything went back to normal.

Second I started to get mysql database error,something like (mysql_connect()< href= function./mysql-connect> database already has a max_user connections'active connections/hermes/waloraweb......

Third : suddenly i have 100's of new users with nonsense names Like : hbxzrtvbsy and so,then I started to have New members verify their emails before sing up

fourth: Yesterday my site started to give me a 404 error and my admin control panel disappeared.

Every time I try to get to my site or my admin CP ,all I get is

http://Acaentrenos.net/install/install.php

thus no web page and 404 error stating that my page has being moved or the name has changed.

Nevertheless to say that I have restored my back ups up to a week ago and nothing
I don't now what to do,since this is beyond me.
my only solution is start since the beginning and reinstall Vbulleting and start from scratch

Any thoughts on this Matter ?

Any input will be greatly appreciated and looking forward to learn from this experience.

thank you