You will have to contact Tech Support in these circumstances. There is no workaround that I have seen, but I suspect you have gone through the related threads already on GeoNet.
There's a workflow through MyEsri to recover the license in this scenario: https://community.esri.com/groups/technical-support/blog/2017/06/12/recover-lost-licenses-from-my-es...
If that is unsuccessful, definitely contact Tech Support. Hope that helps!