pdflatex.exe is part of a whole suite of software called a TeX Distribution. You can't just download the executable. There are two main distributions available for Windows: TeX Live and MikTeX. Both are very good. Whether or not installing them and learning enough LaTeX to solve your problem is a worthwhile effort may well depend on how often you are likely to do what you're doing.
Here are links to the distribution download pages:
See the following question on the differences between the two distributions.
What are the advantages of TeX Live over MiKTeX?
If this is a one off type situation, you may also want to take a look at some of the online LaTeX compilers:
Compiling documents online