how to stop page intialize

Question

 i have a textbox and a search button in the update panel.outside the panel another textbox is there.my requirement is that when i click on button one popup should display from another page using query string value and that query string value get from textbox.according to query string in popup page i bind the grid view.when i m select any record that value shouldcome to my main page. values are coming but i am facing the problem that what data are in textbox it is becoming empty.because i have 3popup and 3different popup page are there.so please some solution.i lost almost 2days for this silly problem bt no answer get.so plz help me