asp.net c# asmx file help?

[Ishida]

I have a popup box which allows users to search for something in my database and add it to a list. I organize the sort by letter and whenever the list gets re-filtered (by letter) all the old checkbox values are lost. I cannot seem to save anything anywhere because there is no 'constructor' in the asmx file. Whenever the page reloads or refilters.. it calls the constructor which reinitializes my list. Any suggestions / ideas? I tried to make a temporary list.. but that doesn't seem to be working properly because it doesnt register until i close the window and reopen the search.. blargh.