Fill out Form 1048
To search for lost savings bonds, go to the U.S. Treasurys website at treasurydirect.gov and fill out Form 1048, which is titled Claim for Lost, Stolen, or Destroyed United States Savings Bonds.
Form 1048 from treasurydirect.gov:
https://www.treasurydirect.gov/forms/sav1048.pdf%20
Fill out as much of the form as possible, Tayne says. Try to obtain the Social Security numbers of the purchaser and estimated timeframe of the purchase.
Verify for your form
Once you fill out your form to the best of your ability, dont just sign it. It needs to be certified. Justin Pritchard, a financial adviser at Approach Financial, says this isnt easy to do. The hardest part of the process is getting your signature certified, Pritchard says. Youll need a signature guarantee or another acceptable form of certification to complete the process. Unfortunately, a notarized document is not sufficient.
To get your form verified head to your local financial institution, such as a bank or credit union. There you will sign the form and have it certified by the institutions certifying officer, not a notary. Contact your bank or other financial institution ahead of time to find out if they have a certifying officer and set up an appointment.
More:
https://www.bankrate.com/banking/savings/how-to-find-lost-savings-bond/
Best of luck!