3 Great Methods for Reclaiming Lost Backlinks

Reclaiming old backlinks is the easiest and most efficient link building method you can perform.
I love digging into what I like to call the "catacombs" of large, established websites that have many years of history behind them to find little bits of link gold.
There are numerous methods to reclaim old backlinks. The three greatest methods for reclaiming lost backlinks will be found on pages that are down or redirected, are buried in old content, or used to link to you in the past.
In his great article on the topic Link Equity Salvage: 7 Steps for Finding Your Long-Lost Links,Garrett French breaks down this process into several broad steps that every link reclamation effort includes:
Compiling lists of old page opportunities.
Checking statuses and checking links of pages.
Redirecting pages.
1. Reclaim Links From Broken or Pages With Multiple Redirects

Run a Deep Crawl
This can be done using Screaming Frog, IIS SEO Toolkit, Xenu Link Sleuth set to spreadsheet export. Whatever you choose here, the key is deep crawl. Try to grab the whole site or as many pages as possible.
Some edge cases may include:
If you have access to the site, some crawlers have a feature for you to search for orphan pages [Xenu], as mentioned in French's article discussed above.
If you have a large site, consider running the site on a server, so you can give it enough resources to be able to crawl the entire site, without crashing your computer.
Grab all 300 Level Redirects and 400/500 Level Server Response Errors
Create two lists: One with just redirects and one with server response errors.
For pages with server errors, run backlink data and identify errors. This can be done easily by running a bulk backlink checker, such as the one provided by Majestic SEO on Use Fresh Index setting.
For redirects, use a header checker tool to follow the redirects back. Sometimes you will uncover years of nested redirects, as pages have moved with tons of trusted aged backlinks. To do this, run the your redirects through a bulk header checker, such as the one provided by SEOBook or one of the many others that are on the web. If you find that some are nested, rerun this data until you get to the original page. Once you've tracked all the redirects back to their original page, run the list through a backlink checker, just as if you were checking for backlinks on 400/500 level pages.
2. Better Utilize Links From The Catacombs Of Your Site

This method goes back to your crawl of the site. If you were able to identify a ton of orphaned pages or ancient content that has been buried your site, such as:
An old blog that was started, run for only year, abandoned, and replaced.
Old press release section you stopped using or that was in place before you acquired the site.
Old "about" section pages with backlinks, that new versions of pages were created but not redirected.
Old article sections of the site.
Old subdomains that are no longer in use.
Once you've gathered these pages, directories, or subdomains, see if any have backlinks. If they do, redirect the given page to the newer version of the page, the next page up in the information architecture, or to the homepage, depending on your situation.
Sidebar: Especially with tracking down all the subdomains on a site, having access to the site tends to be important to get a comprehensive sweep of all subdomains. I know that you can try to do a dig in terminal – for those of you that are nerdy like me – but most servers don't let you do that because of potential security issues. If you don't have access to the backend of the site you're working on, running a crawl and seeing what search engines have indexed are your best bet for identifying really old subdomains. If anyone knows of other methods, feel free to comment.
3. Reclaim Your Linkrot Backlinks

Beyond the above issues of webpages being moved or redirected, there is a natural "rotting" process that happens to all backlink profiles. Some of the pages with trusted links pointing to your website will go away for a number of reasons. Reclaiming some of these links is a great easy list of relevant websites to canvass.
Also, the beauty of checking for rotted backlinks is that this can be a one time occasional process. It can also be an iterative process if you have a large, established website with a significant backlink portfolio to manage.
There are a bunch of methods for doing this. Here are two you can play with:
Link Tracking Script: You can create a custom script for tracking your links. If you don't have the resources in-house to develop this capacity, check out this great article by Gareth of SEO Doctor, for some great information on this method of reclaiming links and for the script.
Excel: Yes! The Swiss Army knife of SEO tools includes a way for you to accomplish this. Richard Baxter of SEO Gadget, has a great article about this method for reclaiming links, that summarizes how to do it in a more step-by-step fashion.
There are two approaches you can take to backlink reclamation. If you're just starting work on a site or are in the auditing process, you can do this once or occasionally. You can also take a more active stance in managing your backlinks on your website by iterating the process during major site changes or even on a regular basis.