How quickly can you relearn a language?

hi I used to to be fluent in russian, but then completely forgot it due to lack of use once i moved back to my country. what's the best way to relearn a language and how long will it usually take. also will hypnotism work. thank you.

>>6
Many Hungarians who emigrated during and after the 1956 revolution forgot Hungarian almost absolutely. When they are interviewed now and then it always looks weird to me that someone can forget his mother tongue as an adult this much.