I'd say it means "I thought about studying vocabulary, but I'd feel lost and helpless with it". 요리를 하자니 귀찮고, 나가서 사먹자니 그것도 귀찮다. I thought about cooking but I can't be bothered to cook, and I can't be bothered to go out for breakfast/lunch/dinner either. -자니 is colloquial Korean and doesn't translate comfortably into English.

1.막막하다=I don't know= 막막하다 2.단어공부를 하려니 잘모르겠다-I don't know what I 'll study English vocabulary .

1.막막하다=I don't know= 막막하다 2.단어공부를 하려니 잘모르겠다-I don't know what I 'll study English vocabulary .