foreign letter in text

When I prepare text in English, I usually write it on Russian and then
translate it into English. But sometimes these operations for different
reason are separated in time. Initially pdflatex printed in log which are
not English. It was helpful to locate such letters and finish text. Now
pdflatex prints some blank symbol instead of foreign letter. And how I can
locate now foreign letter in text that has about 20 files?

Aleks Kleyn