If they are gone on purpose, you should not do anything about it. It is supposed to 404, when the content does not exist. If you get more products in the future, then it...

Check title tag on your site, using Inspect tool. Does it match the snippet?

If you have rel=canonical fixed already and it didn't help, I'd try to remove those duplicate pages from sitemap. Also check, if there isn't canonical self-reference on t...

Optimize meta tags, submit sitemaps, and improve content. Google can't ignore a well crafted, SEO friendly homepage. Reclaim your search presence!

@ms(4092) Yes, but there's no indication of an error or issue. All other pages are still visible on Google. The homepage is indexed but doesn't appear in search results.

That PHP error means you're trying to read key "host" in an array, but it's not defined (such a key doesn't exist in the array, it has not been set yet). There...

@ms...thanks for the reply. I spoke with Google and they said the proper way is to let it 404. I do like your redirect idea though. Would be good for smaller blogs where...

Did you check your Search Console for possible issues? Or does that mean all the pages are still there except your homepage?

This is good question and a scenario I haven't been dealing with yet. Thinking from user perspective, when looking to hit a page #3 but the page doesn't exist anymore and...

Improve the quality of content on the page. Get some internal and external backlinks for the page. This will bring back your page in the SERPs.