Dear K168168,
I'm Renzo, I'll help you with your question.
If the all Planner plan was deleted, you could try with following process:
1. When a team/group is deleted, it goes to a recycle bin for 30 days, after that period the team is deleted definitively, therefore in an internet browser access the following link:
https://portal.azure.com/#blade/Microsoft_AAD_I...
2. Login with your administrator account, in the left panel click on "Deleted groups"> search for the "team/group" by name on the list> select the group and click on "Restore"
3. The restoration process may have a replication time, wait a few hours, then check in the Teams application if everything appears again.
Also, you can check in the web-client at:
https://teams.microsoft.com