wordpress oops google chrome could not find

Hey guys,

Bit of a pickle here,

We had a website running on wordpress, and someone got in and has done who knows what to it, and now its not showing at all on any level, not as /wordpress or /wp-admin and im not sure how else I can get into the admin as im quite new to this.
Ive had a look for some advice but cant find anything.
Is there a way I can reset everything for wordpress and start the website from scratch? I dont know how to get into anything at all its like im totally locked out apart from the domain and hosting side of things.

the address is http://www.audioconcepts.com.au/ if that helps anyone