After redesigning a site without implementing 301 redirects, how do I fix SEO?

Question

I started a guitar lessons site over 10 years ago and it did well on Google search for several years. Good traffic, good AdSense revenue.

Then I ignored the site for several years. I recently redesigned the site, including making it HTTPS. I decided to do it from ground up since my philosophy on many aspects of guitar changed. I didn't want to copy content from old site.

So now my site has totally different link structure. It shares some organizational characteristics with old site:

• Broken down by hierarchy of categories -> lessons -> exercises

But, being a guitarist first, and web dev second, I rushed with new site launch and overlooked things that may hurt my Google search profoundly:

1. I did not map any of the old site links to new site. Very little content will match. Category pages will match, but individual lesson and exercise pages don't have a correspondence on new site.
2. I submitted new site through Google Webmaster Tools.
3. I saw in Webmaster Tools Panel under crawl errors a bunch of 404 errors for old site links. I marked them as fixed. On new site, I just created a 404 for all pages that don't exist on new site, but I made it a custom page with a message, showing the home page of new site.
4. I reconsidered my link structure on new site and changed it, AFTER submitting new site to Google. I know - stupid. Then I resubmitted via Google Webmaster Tools. I did submit sitemap of new structure though.

So now Google probably doesn't know what to think. It got a bunch of 404s on old links. Then all new links as of step 2 above also are now 404s. So maybe it has categorized my site as not worth touching...

Given these missteps, Should I map as many old links to new site as possible as 301 redirects? If so, how would I see the 404 errors from old site given I marked them as fixed in Webmaster Tools? And will it be OK if several old links have same 301 redirect?

Should I also redirect the links from new site as originally submitted (step 2 above) before I redid the new site link structure (step 4 above)?

My site really does have great content, but I am afraid I have made an unrecoverable error.

Answer 1

You can probaby recover from this. Maybe not 100% but close.

This is what I woud suggest:

Redirect all 404 showing up in Search Console. Point them to the best match. If you have some old pages that you can't match with the new then simply point to the new startpage. Don't forget to point to the https version. It is OK to point several links to the same new page.

This may take some time to complete since you already maked some as fix, but don't worry, they will show up in GSC again as long as they haven't been redirected. Check every week for 3 months. When no new 404 warning shows up you have probaby caught most of the old pages.

Now, if you want to do this properly you should also identify what backlinks you had pointiong to your old website. Try using Ahrefs.com or Majestic.com. In those you can discover broken backlinks i.e. backlinks to pages that no longer exist. If you find any you shoud redirect tha old page to a similar page on your new site. This will give you "linkjuice" and strengthen your new website.

There are more things you could do but if you do this properly you will see a stready incline in organic traffic. Don't forget to test your redirects so you know they are working properly.