How to restore Default VPC that has been accidently deleted for my AWS Account for Mumbai region.

Hello,

Unfortunately, you cannot restore a default VPC once it's been deleted. However, alternatively, you can create a new default VPC again. You cannot restore a previous default VPC that you deleted, and you cannot mark an existing nondefault VPC as a default VPC as well. Check below,

To create a default VPC using the console

Open the Amazon VPC console at https://console.aws.amazon.com/vpc/

In the navigation pane, choose Your VPCs.

Choose Actions, Create Default VPC.

Choose Create. Close the confirmation screen.

To create a default VPC using the command line

You can use the create-default-vpc AWS CLI command. This command does not have any input parameters.

aws ec2 create-default-vpc

Please refer more information here - https://docs.aws.amazon.com/vpc/latest/userguide/default-vpc.html#create-default-vpc