If you have an Office 365 Groups being deleted – either by admin actions or group owner – you can recover the deleted group for a 30 days period.
To recover a deleted Office 365 Groups, you need to use Azure Active Directory PowerShell v2 Preview (available here https://www.powershellgallery.com/packages/AzureAD/2.0.0.98)
Install AAD PowerShell v2 Preview
Open a PowerShell command prompt and run the command and once the new module is installed close the PS command prompt to restart it – if you do not restart the PS command prompt, the required commands to get the delete Office 365 Groups will not be available
Install-Module -Name AzureAD
NOTE 1 You may got a request to update a component called NuGet; accept the request otherwise AAD PowerShell will not be updated
NOTE 2 you may got a second request because the updated modules going to be installed are not coming from a trusted location
Connect to Azure AD
To take advantage of the updated module with new commands, you need to connect to your tenant using the command
Connect-AzureAD
Get deleted Office 365 Groups
To search for deleted Office 365 Groups use the command
Get-AzureADMSDeletedGroup
Recover deleted Office 365 Groups
To recover the deleted group,run the command
Restore-AzureADMSDeletedDirectoryObject –Id <ID returned by the previous command>
You can then check using the PS command Get-AzureADGroup –ObjectId <ID returned by the previous command> or using Office 365 Admin portal to see your recovered Office 365 Group