iPhoto disappeared photos

iPhoto issue - 4 photo events full of pics went missing within minutes after upload from an SD card, canon pics

4 event dates now show 0 pics when hundreds originally loaded & iPhoto

As usual iPhoto asked to delete from the card ... which never does that till upload finishes... I said yes, it did the rainbow spin for 5 minutes or so

pics gone for those event days???

very maddening, they must be somewhere on the card, on the mac computer, in iPhoto somewhere? not sure where or how to look