Hello there,
this can be sadly two issues.
One could be solved, the other not. If the community is not deleted, it could be a UI issue.
So if this is the case and you can not see the Community any more you can solve this with this script /script ToggleCommunitiesFrame()
The other case is sadly not salvageable for us. Since it is not possible to restore a once deleted community.
If this is the case and this happened the deletion can only be done if the person who did it filled the Rank " Owner " . In communities this rank can be shared between different users.