There are a couple of places that may prove to be helpful in this matter:
http://www.savingsbonds.com/salespagelb.cfm - they deal with lost/missing bonds of all types-you'll pay a fee for them to research, however.
I would also check out this link - https://insurance.va.gov/inForceGliSite/liability/ufsearch.htm - as they may be the best way to retrieve the bonds' value and possibly the numbers of the bonds.
http://www.treasurydirect.gov/NC/FoRMSHome?FormType=SBF&site=indiv - this is the US Government's treasury site and this link has forms for all types of missing bonds here you can fill out yourself. You can also contact them for more detailed information. - they would be the agency that actually reissues the bonds for your brother.
I was able to find a phone number for a Bonds expert in the Treasury department. I'm unsure how current the information is, but, it's a place to go.(NNN) NNN-NNNN
You can also write to them at:
Bureau of the Public Debt
P.O. Box 426
The VA *might* be able to tell you the numbers on any certificates or
bonds issued to your brother if he doesn't have them somewhere. Since these are older records, they may not be able to help, but I'm sure they will try their best. Again, I dug up an email address to use. Not sure it's the current one, but it's worth a try.
The email contact for the right person at the VA is:
however, if that email bounces, you might just go to the VA website above, and contact a general email address and go from there.
You definitely have your work cut out for you, but.....it could definitely pay off for your brother if you are successful.
Please let me know if I can help further.