Broadly, the problem outlined here is the same as How to convert PDF to (La)TeX?. The reason is that at best the various additional files contain only a small subset of the information needed to understand the structure of the
.tex source file. I don't want to repeat all of the info in File extensions of LaTeX-related files, but as a summary:
.blg files are logs: they tell us what happened in the LaTeX and BibTeX runs, respectively. That will be useful in working out which packages were used in the
.tex file, but that alone does not get us very far (no custom settings or actual input).
.bbl file may help with the bibliography part of the document. If you did not using
biblatex then the
.bbl file is a formatted bibliography, but if you used
biblatex then it's not. Moreover, it does not help with the citations that link to the bibliography, and most of the time the bibliography will be a relatively small part of the entire document.
.aux file tells us about information transferred between LaTeX runs, so for example labels used in the
.tex file, but not where they might have been cross-referenced, etc.
As you'll see, the amount of information in the various additional files is at best quite limited, and in most real documents will form only a small part of what's needed to reconstruct the
.tex source. Thus there will still be a lot of work to do extracting data from the
.pdf, and it may well be easier to ignore the other files and 'start from scratch', reconstruction-wise.