PdfLaTeX in Texmaker doesn’t work: “Could not start the command”

The paths to your LaTeX und PdfLaTeX are wrong. latexsym.sty is a package, which isn’t ever gonna compile anything, and pdfetex.exe is a compiler, but definitely not the one you’re looking for (see e.g. Glossary of TeX and LaTeX terms). If MiKTeX is in your PATH varible (which usually is the case if you installed it normally), you don’t need to specify the full path to the directory, the name of the compiler/program with the desired options is entirely sufficient. Basically, you just enter what you would enter when compiling from the command line, just with %.tex as a placeholder for the file to compile. So here’s the right (standard) configuration:

LaTeX: latex -interaction=nonstopmode %.tex

PdfLaTeX: pdflatex -synctex=1 -interaction=nonstopmode %.tex

Sorry for opening an old issue, but the above did not work for me. What worked for me was to "Refresh FNDB" from MiKTeX Options (Start -> MiKTeX 2.9 -> Maintenance -> Settings). Note also that a warning box popped up after clicking Settings, which goes away after refreshing FNDB.

(This is a bit different than the OP's problem, but the error message is the same. I hope this helps someone else:)

Having never used LaTeX before, I started off by installing Texmaker, and encountered this error. I didn't know that the LaTeX tool is not bundled with the editor, and must be installed separately.

In my case, I was able to fix the above error message by downloading the proTeXT tool from the LaTeX site:

http://www.latex-project.org/

...and running the MikTeX installer.