iv'e been hacked?

Hi everyone I’ve just finished making my blog packing it out with info and pictures and someone’s only gone and hacked it? completely wiped out my site and put one page of rubbish with loads of numbers and silly music playing. I would be greatfull if anyone knows how to get around this so I can get my work back because I cant even log into my meta as everything has completely gone. Any ideas?

Thanks
Dan..