Recommend some good bands that don't sing in english.

Burzum for the most part sings in Norwegian
Coutess "Helling Vurr" is in Dutch
Lots of Darkthrone songs are in Norwegian especially on "Transilvanian Hunger"
Drudkh (I think)
Nargaroth for the most part sings in German
Ulver for the most part sings in Norwegian
 
Korrozia Metalla and Kolovrat are thrash bands that sing in Russian. Triskelon is a death metal band that sings in Swedish. Of course, there is tons of black metal that is not in English, but I don't know if you are into black metal.