is there a safer in Hebrew about מנהגים what they did in Lithuania before the war .for instance וואכנאכט (ליל ברית, or אָפּשערן and a lot more?
The most comprehensive book on Ashkenazic (including Lithuanian customs) is Ta'amei HaMinhagim u'Mekorei HaDinim by R. Shperling. Otzar HaMinhagim of R. Y.D. Eisenstein is also very helpful. If you want to know specifically about the Lithuanian yeshiva world, From V'lozhin to Yerushalayim of R. Meir (Berlin) Bar-Ilan has tons of first-hand personal accounts.