Just started PhD, feel lost and abandoned
You have good reasons to feel abandonned, and it is the good moment to decide whether or not to pursue a PhD. This decision is a difficult one to make, and you will need to reflect on your professional goals and alternatives for you. Starting such an endeavour, and not being excited by the subject is a big deal.

No, you are not wrong to expect more. A PhD student is not a researcher you pay to have something done. A PhD student is someone with some skills, but that still need training.

There is things you can do if you want to continue your PhD on this topic:


Ask your advisor to include a coadvisor with expertise in this new subject. You could even try to find yourself a coadvisor.
Find course on this new topic, either at your university or at another. Sometimes it is possible to take classes at another university and have it include in your program. It depends on your country and university.
Make the subject your own, by developping your questions around it. A little bit difficult when you are starting, but this is doable.


... and this is not an exhaustive list.