What else is lost

I know that I received my season tickets to the local concert association events for the coming season.  I marked my calendar for the events I didn't want to miss and I know that I put the tickets back in the envelope.  What I don't know, where did I put the envelope?  I've looked for about 30 minutes, I feel the frustration level increasing and  I know that I need to let it go for tonight.  It's late, I'm tired and I'm only going to feel worse because I'm certain my search will continue to be fruitless.  
I read another's blog post about how she could not find "something" she put away for safe keeping.  I smiled as I read her account of the search but I can assure you, I am not smiling now. Someone helpfully suggested she get a notebook and record things as she put them away for safe keeping and I thought that a worthy suggestion at the time.  But as I consider it right now, I'm afraid I won't remember where I put the notebook!  If I can't find the notebook, how will I know what else is lost???