Works. Every. Time.
If you’d prefer a more traditional prayer, you could try this Novena to St. Anthony:
St. Anthony, perfect imitator of Jesus, who received from God the special power of restoring lost things, grant that I may find [name of item] which has been lost. At least restore to me peace and tranquility of mind, the loss of which has afflicted me even more than my material loss. To this favor, I ask another of you: that I may always remain in possession of the true good that is God. Let me rather lose al things than lose God, my supreme good. Let me never suffer the loss of my greatest treasure, eternal life with God.
But, for the record, the short version works, too!