First find out whether Google has your site at all. Search for site:yourdomain.com. If nothing appears, the site is not indexed and the cause is technical or the site is very new. If pages appear but not for the searches you expect, the site is indexed and the problem is ranking, which is a different job.
The best tool for both is Google Search Console. Add and verify your site there; it is free and shows exactly which pages are indexed and why others are not.
If the site is not indexed
1. A noindex left over from development. Staging sites are often set to “discourage search engines”, and the setting survives the launch. Check the page source for noindex and the HTTP headers for X-Robots-Tag. In WordPress, see Settings → Reading. Fix: remove it, then request indexing. Guide
2. robots.txt blocks everything. Open yourdomain.com/robots.txt. A Disallow: / under User-agent: * stops all crawling. Guide
3. The site is too new. A brand new domain with no links can take days to weeks to be crawled. Submit a sitemap in Search Console and request indexing for the homepage.
4. Nothing links to it. Google finds sites through links. A site no one links to is found only through Search Console. Get it listed where it naturally belongs: your social profiles, directories in your field, partners.
5. The server refuses Google. A firewall, CDN bot protection or country block can answer Googlebot with 403 or an error. URL Inspection's live test shows what Google gets. Guide
6. The content is invisible without JavaScript. If the HTML is an empty shell and everything is drawn by scripts, indexing can be slow or partial. View the page source: the main text should be there.
7. Every page canonicalizes to one URL. A theme or plugin bug can point every page's canonical at the homepage, and Google then indexes only the homepage. Check a few inner pages.
If some pages are not indexed
8. Google crawled them and chose not to index them. Search Console shows this as “Crawled – currently not indexed” or “Discovered – currently not indexed”. The fix is usually better and more distinct content and stronger internal links. Guide
9. They are duplicates. Google indexes one version of similar pages. Guide
If the site is indexed but you cannot find it
Search for your brand name. If it does not appear on the first page, check for a manual action in Search Console (Security & manual actions) and make sure your title tags actually contain the brand. For other searches, the site is indexed but not ranking; that depends on content, relevance and links, and takes longer.
Builder sites (Wix, Squarespace, Canva sites, Shopify) have their own visibility switches; make sure the site is published, the password protection is off and search engine visibility is enabled in the site settings.
Check the whole site in one go
SignalCrawler checks the technical causes above in one audit: noindex tags and headers, robots.txt rules, canonical tags, server answers to crawlers, content that needs JavaScript, sitemaps and internal links. A free scan takes a few minutes.