korean drama where girl has one sided love to bad and cold guy.

Que Sera, Sera , baby & I ... I dropped both of them but maybe you would like it :)
thanks guys i will check them^^
There are a few, assuming that you mean that whilst initially the love may be one sided that at least at some point it is reciprocated. 

With that in mind in order from funny to melodramatic,

Oh my Ghost
Pasta

The Greatest Love
Secret Garden

Fated To Love You
Innocent Man


I would second Que Sera Sera. I really liked it.