After 40 days of work on an old domain with 50 posts and aprox 30-40 clicks daily clicks, all keywords suddenly dropped in rank, resulting in zero visitors. What could be the cause?
Google regularly updates its algorithm to improve the quality of search results. These updates can sometimes cause websites to lose rankings, especially if they are not following best practices. Ensure your content is written well, has good info, and is related to your keywords. Rankings take a while to bounce back after they go down. Don't expect a quick change, dude. Just keep working on your website and SEO to get back those rankings.
Possible Google update, BUT. 1. Check indexing in Google console. 2. Have you worked on external optimization? You may have had external links that have fallen off.
You probably got hit by the most recent Google Core Algorithm Update that started rolling out on August 22nd. It should finish rolling out any day now/this week. This is the second Core Update this year. I would refer you to this resource if you've been hit, along with checking on-page factors and backlink profile.
Seems like either you bought a expired domain and working on that or changed the website completely .... There can be some other issues also .... So first check GSC (Google search console) that pages are still indexed or there are some message from Google .... No one can say exactly without check GSC and your website.