Azure App Service is a service used to create and deploy scalable, mission-critical web apps.
normally soft-delete is enabled by default for most of the services
but you have limited time to recover after deletion like
Azure SQL Database - 7 days for basic tier
and Azure App Service - 30 days
if those days passed you cannot recover if you do not have any backup etc.
you need to check for your activity log first
and look for Delete operations to check when thoseresources deleted also check what is the timeframe for your resources