As no-one has replied to you, I'll let you know what you'll need to do.
You'll need to make a ticket on
Discord under the
Help and Support section. From there, use the command
$ticket open lostrank and a member of staff will reply to you about how to get your rank back.
Bare in mind, whoever replies to you will ask for your IGN and what server you played on originally. Seeing as how you used to play Silver, and it's no longer alive - I believe they would transfer your rank to Gold. However, they may transfer your rank to Sapphire instead as that server was the one that merged with Silver.
Make sure you've also got your original purchase receipt that you received in an email from Complex - as that will have your original transaction ID in it.
Basically, it's worth a try!