Do you have any mapping software (Lowrance or others) that can read iFinder files? If so, save your data (all) on the receiver, to the card and open the data file with that mapping software - they may be easier to find there.
Short of that, if they dissapeared... well, you must've accidentally deleted them. The trails can be changed, removed, lost if they are overwritten - once you hit the limit for points in the trail record, it starts to overwrite the trail from the beginning but, Events (Icons) and Waypoints can be only removed by deleting or individually editing them. Even if you load new data file into the unit, all of the existing waypoints are preserved - new ones are just appended.
HTH