无从下手 literally means 'no path from which to lower the hand' — there's no obvious place to lay your hand to grab the problem. Use it for daunting, tangled, or unfamiliar tasks. Synonyms:
不知所措 (bùzhī suǒcuò, at a loss what to do),
一筹莫展 (yīchóu mòzhǎn, can't think of a single plan).
