Luther: when Luther found out you had gotten kidnapped, he did whatever he could t find you on his own. If he was unsuccessful he'd turn to his siblings and ask for their help, which they all are happy to.
Diego: Diego wouldn't tell anyone at first. He'd internalize his feelings and track down whoever took you. If anything happened to you, all hell would break loose, he loves you and wouldn't let anything happen to you were you'd get hurt. If he didn't find you soon he'd start lashing out at his siblings until they demand he tells them what is going on. Diego wouldn't accept their help, but he wouldn't stop them from tagging alone.
Allison: if you got kidnapped, Allison would immediately go to her siblings for help, not quite knowing what to do.
Klaus: Klaus starts panicking almost immediately after finding out you had been kidnapped. How was he going to save you? His power is kind of useless in a situation like this. Once Klaus calms down he goes to Diego for help and the two of them rescue you.
Five: all hell would break loose. Or at least once Five found you. His siblings had no idea that you were gone until Five came back to the house with you. You were fine, but the people that took you, they were in a world of hurt.
Ben: as a ghost, there wasn't much Ben could do to save you, so he went to Klaus and filled him in and they two of them played detectives until they found you.
Vanya: before she found out about her powers, Vanya would go to the police if you got kidnapped, but once she realized that the police would most likely take forever to find you, she would head to the academy and beg her siblings to save you.