You're hosted on a shared server. So, contact the webhosting company that hosts the site and ask them for help.
If you don't have that information, and only if you registered the domain separately from your webhosting (always recommendable - here's one very good example why!) the next step up the drastic but temporary countermeasures scale is going to the registrar (the company where you registered the domain loulisa.net for your site, e.g. GoDaddy or Network Solutions) and ask them to remove the DNS settings. That at least will make your site completely inaccessible, which stops your site being poisoned in search engine rankings.
Meanwhile, continue trying to get in touch with the webmaster, and for next year's summer vacation, make sure you have contingency plans in place.
Once again, here's a very good example of why that is a good idea, instead of relying on "other people taking care of it."