
Hi,
Here is the procedure to restore a user : https://learn.microsoft.com/en-us/microsoft-365/admin/add-users/restore-user?view=o365-worldwide
You have 30 days to restore a deleted user.
Source : https://learn.microsoft.com/en-us/microsoft-365/admin/add-users/restore-user?view=o365-worldwide
Feel free to put this answer as accepted if it helped you.
Sincerely,