Consider trying the Transliteration module?. Here is a quote from its project page:
... it takes Unicode text and tries to represent it in US-ASCII characters (universally displayable, unaccented characters) by attempting to transliterate the pronunciation expressed by the text in some other writing system to Roman letters.
As a sample, it transforms an URL like mydomain.com/последние-новости-в-Украине-и-мире
in something like mydoamin/poslednie-novosti-v-Ukraine-i-mire
.
Other modules that might help to solve this question: