down on one's luck

be down on one’s luck (not lucky, not happy or positive; be experiencing a bad situation or to have very little money) — быть в беде, несчастье, в тяжёлом положении; счастье изменило; в полосе невезения

Example 1: He did me a favor when I was down on my luck.

Example 2: With no money and no job, he's been a bit down on his luck recently.

also
[bad patch]
[dry spell]
[tough time of it]
[Hard lines!]
[черная полоса]
a run of bad luck
[бутерброд всегда падает маслом вниз]
полоса невезения
полоса неудач
[не везет так не везет]

opp.:
[winning streak]
[lucky streak]
[на гребне волны],
[на волне успеха]