Can't resize shrunken boot partition to fill empty space
First, try to delete the Bootcamp partition using Boot Camp Assistant.
I had a similar problem, and Boot Camp Assistant didn't recognize any Bootcamp/Windows partition, but in Disk Utility, the size of total space of my 1 TB HD showed only 850 GB of total space. The other 150 GB (from a failed attempt to create a bootcamp partition) did not show in the Disk Utility or anywhere else.

Then, quite by accident, I created 2 additional partitions using the Disk Utility.  The total space of the 3 partitions showed as 850 GB. However, I then used the Disk Utility to delete the 2 additional partitions which I had created, and it allowed me to specify a resized single partition of 1 TB.  After I had deleted the 2 additional partitions and resized to a single 1 TB partition, the total available space showed up as 1 TB (or actually, 999.97 GB), which seems as though I recovered all of the unused drive space.  :)