无功而返

to return without any achievement (idiom); to go home with one's tail between one's legs

and / as well as / and so / but (not) / yet (not) / (indicates causal relation) / (indicates change of state) / (indicates contrast)

not to have / no / none / not / to lack / un- / -less

meritorious deed or service / achievement / result / service / accomplishment / work (physics)

to return (to)