While a reinstallation of the core WordPress files is often a good call to cut malicious code from a site, there are other avenues of detection to pursue first.
Problems with phantom edits
Sometimes folks edit stuff and changes don't show up. Damn, that's frustrating.
Are you working on the right web page? This sounds silly, but it happens all the same, sometimes for instance when a host relocates a server. To be sure, add a comment
<!-- hey! --> to a theme template file, clear or disable your browser cache, and refresh the page. On the page, right-click and choose to view the source code to see if the comment is there (<!--comments--> don't show up on a live page). If not, talk to your host to find out where the files really ...