Y am i being charge with like 11 conts including ?

if a girl 14 accuse you of 19 but it did not happen and she went to the hospital and got a kit but the accused Denys anything happpend why are they arresting him what do they have and do you think case will be dropped in preliminary hearing what are the chance of conviction and the accused has an witness that can back him up so its she said they said why did the da prosecute?