I hate this feeling.... HELP!!!?

Well not so long ago, I was given a brand new expensive wallet for Christmas and around $200 Christmas money and a few vouchers for some stores. One day I took it into town and left it on a table for around 30 seconds and I turned my back away. When I turned back, it was gone. I looked EVERYWHERE and I still couldn't find it. I became really sad and depressed because a few days before that I thought I lost it and I spent a whole day looking for it and when I found it I was so happy! But I FOOLISHLY took it into town with all my money in it. I was crying for ages because I thought how hard it is to get money nowadays and how much work the people who gave the money to me had to put in to earn it. How do I resolve what Ive done??? How do I forget this feeling? HELP!!!! :(