If a wood structure, then there is a wooden header behind the block and above the door that carries the weight of the building.

Your contractor will need to remove the old header, increase the size of the opening and install a new header.Good Investing...

Lots of old houses were built before codes were enforced so we see lots of things like missing headers or strange methods for hanging joists or cut out structural elements for heating ducts and things. 

I have removed a wall and installed an LVL header, and used reclaimed beams from my W2 job as support.

Oh, one thing though, where did you go to change the header at the bottom of your posts?

Be sure "My list has headers" is not clicked:Click OK.

Did the inspector actually open the walls at the headers to verify they are broken, or did he or she just make an assumption that it's structural damage?

Not ideal but he will be able to hide the header which will help to open it up.

Joists have to be properly supported and headers properly installed.

Jason, somehow I could tell when reading your comment that you must know a few things about landscaping before I saw it in your header that you're in the biz, all good ideas and I always do the yard work including at least some landscaping work on any flip, even on a cheap house people will be turned off right away when they pull up and the first thing they see is a crappy looking yard!