he should have never deleted files it is simply impossible to know what he did.
Has anyone ever compiled the 10 commandments of Satoshi? (Or whatever number is required to have them all.)
Here's one of them that fits the current context:
Sigh... why delete a wallet instead of moving it aside and keeping the old copy just in case? You should never delete a wallet.
You shall never delete a wallet because you never know how and when you may need it. It simply doesn't make sense, especially when it's a wallet full of non-deterministic random private keys like the old wallets before HD wallets were established.
And I would extend the "do not completely delete" mantra to mnemonic recovery phrases, too. If you think you don't need it, fine but still keep it. You can lower storage security, but simply don't delete it completely. There may come the day where you'll be happy you haven't deleted it.