Unfortunately there is no way to un-delete a resource in Azure, with few exceptions (Storage Accounts in some situations). A Front Door is just a configuration, so you should be able to re-create your Front Door with the same certificate. You will need to re-configure the Front Door as well. Azure does not save configurations of deleted resources .
If you have created a support request on the subscription in the past 3 months, there is a chance we might have a copy of the old configuration of your Front Door resource. Email the owner of the support request, or post the Support Request # (SR#) here, and I can try to find it.