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The deleted data are not actually wiped away from your phone, and to recover it remember don't save new data to your computer, or deleted data won’t be recovered. Try to use Android file recovery tool to help, See this guide: how to recover deleted files on Android

It is inevitable to fail to upgrade your iOS devices. When that happen, you may lost all your data. So before updating you need backup your iPhone data to computer.
However you can recover lost iPhone Data after Upgrading to iOS 8

It is inevitable that you may lose some important data like contacts, text messages or others from the phone during the daily use. So it is highly recommend implementing a regular backup plan in order to minimize any chances of permanently losing data.

How to Recover Deleted Contacts from HTC ...

Thanks to the Android SMS+Contacts Recovery tool, I got back all the lost contacts from Android. For other data, you need sd card data recovery tool.

As I know in order to recover files from Samusng, we need SD Card recovery software which can deeply scan the partition able, leader record, FAT and file/directory records, etc. and extract them into a normal directory.