ИСКАТЬ/НЕ НАЙТИ ДНЕМ С ОГНЕМ

[iskat'/n'e nayti dn'om s ogn'oin]

To search for someone or something by day with a light.

To seek in vain, to look hard for someone or something with little chance of finding; it's nowhere to be found.

Cf. You will not find it in a month of Sundays; you can't get it for love or money.