First secure access to the domain, hosting, website/CMS, business email and DNS. Do not rebuild or make major changes until you know what you can access and have a safe copy of the existing site.
The first priority is control, not a rebuild.
If your website developer has stopped responding, it is tempting to immediately find someone else and start rebuilding. In many cases, that is not the first thing you need to do.
1. Find out who controls the important accounts
Start with the domain registrar, hosting account, website or CMS administrator, business email, DNS provider and any third-party services the website depends on. Write down what you can access and what you cannot.
2. Secure the domain and hosting
Your domain and hosting accounts are especially important because they determine whether someone else can keep the website online, change DNS or move the project. Make sure the business owner has direct access wherever possible.
3. Preserve the existing website before changing it
Ask for or create a safe copy of the current files, database and configuration before making major changes. A working site can be easier to rescue than a rushed replacement.
4. Decide whether the project needs rescue or rebuilding
Once access and the current setup are understood, you can make a much better decision about fixing the existing site, changing the technical setup or starting again.