Heroic Chest
I’m pretty sure you get that chest only once per account. So maybe you forgot to put the chest in your bank and deleted it with your character? If you fill out a help ticket support may be able to help you.
I believe it’s been deleted with said character. You should have banked all items before deleting your character. Also you didn’t have to delete your character to play PvE with your friend, you could have guested to his server. Unless of course you were planning on playing WvW on the same server. You might want to submit a ticket and explain what happened, who knows you make get it back.
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