Unless your virgin.net email address is correctly associated with your current Virgin Media account and is shown in your My Virgin Media,
or you transferred from Virgin National (the old Virgin ADSL service) to the Virgin Media cable service - taking your legacy email account with you,
or you downloaded and backed up all legacy emails when you moved to the cable service, then I'd suggest that resurrecting a virgin.net email address from 14/15 years ago is highly unlikely to happen.
Virgin Media have been aggressively deleting legacy email addresses, ones not associated with a current broadband account, usually without warning. This is happening with email addresses currently in use, let alone ones from so far back.
I wish you well, but be prepared to be disappointed.
It's What I Do.
I Drink and I
Remember Things.
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