Not quite sure how to word this, but I'm looking for an idiom or phrase/saying that describes when somebody who's done nothing to deserve it has hit a streak of bad luck. Wish I could be more descriptive, but that's about as well as I can elaborate on the idea.
To be dogged by misfortune
is an expression used to convey the idea that you are constantly unlucky.
- to pursue or follow after like a dog.
The Free Dictionary
Jinxed could refer to someone who is suffering a period of bad luck.
jinx (jĭngks) n. 1. A person or thing that is believed to bring bad luck. 2. A condition or period of bad luck that appears to have been caused by a specific person or thing.
However, this usage has connotations of being cursed, or having an extrinsic cause.
String/streak of bad luck;
an albatross around one's neck;
Can't catch a break;
Can't win for losing;
can't stand up for falling down;
born to lose;
it never rains but it pours;
when troubles come they come not single spies but in battalions (that one is from Shakespeare);
born under a bad sign; losing since the day one was born;
born to suffer
- Schlemiel: An awkward and unlucky person for whom things never turn out right.
How about these?
destined to fail or have many difficulties; unlucky.
likely to have an unfortunate and inescapable outcome; ill-fated.(You can say 'doomed for life' is you want to specify that the person being referred to is going to be unlucky for the rest of his life(though I understand that it's a completely hypothetical situation))
Source: Oxford dictionaries
These are just words, not phrases/idioms but I think they convey the desired meaning.
you mention "who's done nothing to deserve it..."
There's a useful phrase,
No good deed goes unpunished.
Nowadays I'd punctuate it like this: No good deed goes unpunished :/
This is precisely what you say when you've done something trying to help someone else, and, by unlucky happenstance, you suffer because of it.
(It's rather like the outcome of "don't stick your neck out!" if you failed to listen to "don't stick your neck out!" :) )
For example, one time I was driving along and I saw an actual cliché of a pregnant woman, also with another small child, who was having car trouble.
I pulled over to help, topped my car, opened the door and ... scratched up the door of my nice car on a stone wall. Marvellous. "No good deed goes unpunished."
Another time - these things often seem to involve cars - I had just got a brand-new lovely car that day. Someone needed a ride to the airport, so I rushed to help. I managed to leave a work knife in the back pocket of my jeans -- ripped a hole in the lovely new leather of the driver seat. "No good deed goes unpunished!"
Perhaps this is what you're looking for?
If not, someone can downvote me - since no good deed goes unpunished :/
You can say someone is having a "losing streak". This is more typically used in the context of gambling, but can be a general-use phrase about how a person's life is going at the moment, as in "John is having a losing streak in his job hunt; after 5 interviews, he's not had a single call-back for a second, nor an offer."
"Down on his/her luck"
down on one's luck, in unfortunate circumstances; unlucky: She hated to see her old friend so down on her luck.
You might say that the person is chronically unlucky or has chronic bad luck.
- (of an illness) persisting for a long time or constantly recurring.
- (of a person) having an illness persisting for a long time or constantly recurring.
- (of a problem) long-lasting and difficult to eradicate.
Synonyms: constant, continuing, ceaseless, unabating, unending, persistent, long-lasting; severe, serious, acute, grave, dire
You might also simply say "he is bad luck."
If it's a particularly long streak of bad luck, you may call the person a born loser.
(informal, often derogatory) A person who is habitually unsuccessful or unlucky or who is prejudged to be a failure in life, especially one with a defeatist outlook.
To be snakebit
Definifion see here: http://www.merriam-webster.com/dictionary/snakebit