How to get the selected item for auto complete text box

Question

Hello,

I'm passing 3 column fields in AutoComplete Text Box like Registration Number, Applicant Name and Guarantor Name from c#. Now i would like to pass the corresponding ID but it should not display in autoComplete text box and when i select any string in autocomplete text box i would like to get that particular record with ID in c#. How would this possible plz help me so soon as possible. I'm struggling for for past couple of days.