One of my major high traffic websites was nearly crushed during a transfer...moving from one host to another. Everything that could go wrong...did go wrong and more. The site was off line for weeks.
The major site was saved, except for a few images. The blog was saved....may the rest of the sites rest in digital peace-grin.
This Internet disaster was NOT a disaster.
All the 'on site SEO' on the main site and the blog are all in tact. On site SEO are the key words that you include in your meta section if you build sites the old fashoined way (I do), or in your SEO section for most site builders. These keywords tell the search engines what your site is all about.
When you include on site SEO, your result is free, targeted traffic... this is the BEST traffic and will be traffic that you'll love for free!