Can't recognize subtitles after format
 

hello,im greek but im studying in bulgaria so sometimes i use the one or the other language.Recently i have done a format and my laptop (windows xp) can't recognize both languages,before the format everything was working perfectly...
the solution is different than the commons i see in the internet like subtitles fonts and etc.Is there any programm for auto-coding languages that i have forgot to download or...?