I have saved all of the HTML file from an old blog that I can no longer access. Can I upload that into Blogger or some other place so that the website can be seen again?
What do you really want to do with those HTML files and what do those HTML file contains?
If you have a web hosting account you can upload it there to put the HTML documents online. Alternatively you can upload it to Dropbox for free (in the public folder) and share its direct link to people.
If you are talking about an XML blog content file exported from a Blogger blog, then yes you can import it into another Blogger blog (or even WordPress site). In Blogger, navigate to the
Settings tab -> Other -> And click the
Import Blog link, browse to the XML file and upload it.