What else can i do to get my daughter back ?

my name i tamara snaith an d i am 19 yrs old i just had a baby 2 month ago .. but my bby was taken away from and place into her grandparents house and i want to know what can i do to get her back and why was she taken away from me.. ? (when i was smaller i was hospitalize 10 times so i was but into foster care after there i was doing real good i was incapacitated when i turn 18.. but when my bbys daddy cheated on me i got real depress but i dnt want to kill my self i ask for my meds so i cn stop feeling like that after i got my meds n all i was doing real good even though he would call n txt me just to bug me .. when the bby was born (preemie) i would go see her every day n her dad only 2 .. n they still gave him mire priory than me ) pls explain i love my bby girl n i would do anything