How can someone obtain award memos if a soldier lost theirs?

The ERB is blank because the Guard ERB is generated by an entirely different system than active duty. When all three components go live on IPPS-A, then all three will have an ERB from the same system. At least that step will be easier next year.

If the Soldier didn't keep a copy of the award(s), that's on him. He should have been providing a copy and following up until it showed up in iPERMS, (and that game can be a struggle in any component). But career management, to include one's own record, is an individual sport, and you get out of it what you put into it.

If their old BDE S1 does not have an archived copy from getting the 638 signed, and the Soldier didn't keep a copy, then the Soldier is SOL. Use it as a teachable moment to keep your paperwork.

Most awards use a DA638. You can try contacting previous units but dont get your hopes up. Also keep authority levels in mind when looking.

Understand your concerns regarding your situation. When you're referring to memos for Awards. It sounds like you lost your Unit Awards Memos. Here is the weblink to support you during deployments.
https://history.army.mil/html/forcestruc/wotawards.html
https://www.hrc.army.mil

Maintaining a copy of an award is an individual responsibility and EVERYONE knows how important it is to maintain a copy for yourself. If the Soldier don’t have a copy, it’s not in their iPerms, and the unit don’t ha e it in their system, how do you know the award actually exists? I can see maybe one award but 5? Unlikely. Without proof, there is no way to validate the awards and 5 awards missing is way too many to give the Soldier the benefit of doubt.