Usually data can be lost or deleted from your PC, gadget or removable area due any number of various reason. Beyon hardware error or malfunction, the most common data loss reason include human error, disk formats, improper device handling. It can make any user fell frustrated as inaccesible data usually brings wastage of time and energy (user's energy), often it brings loss in business reputation and/or downtime and wastage of money.
There are a lot of data recovery software over the internet, a simple search with any search engines. I've listed a few programs that are in the top list.
Digital Rescue Premium 3.1
Digital Rescue Premium have impressive features, practical utility and reliable effectivenes. It recovers lost emails, lost and deleted photos and video, restore deleted files by historical versions, have automatic & quick scans, Recovery-By-Search (deep search finds delete files by name, type, file extension and more), powerful batch recovery, quick preview. It have an easy-to-use interface and multiple device support.
Bad stuff: it does not have product support over the phone and online chat.
Advanced Disk Recovery
There are provided 2 types of scans: the quick scan uses the master file table and the deep scan uses file signatures. Advanced Disk Recovery scans the entire system for deleted filed and folder (on hard drives, partitions, external devices, CDs and DVDs) and gives the user the opportunity to recover them. Once the scan is complete the user can either preview the files and folder or to recover them to the location he/she wants.
Advanced Disk Recovery also have the option to save the scan session if the scan is aborted, it have an Advanced Filter option to recover desired data, restore multiple items to location of choice, checks file header for extension and corrects them if changed.
Bad stuff: doesn't support RAID drives.
Recover My Files 4.6

Bad stuff: GetData (the publisher) does not provide phone support, but they have live support via online chat.
Data Recovery Wizard 5.5
As the name suggest, Easeus Data Recovery Wizard has an extremely easy to use data recovery process. It provides 3 data recovery modules: deleted file recovery (recover deleted or lost files emptied from the Recycle Bin), complete recovery (recover filed from formatted hard drive) and partition recovery (recover data from deleted, lost or damaged partition). It can also recover the lost files from dynamic disk, RAID, USB external hard drives, memory card, memory stick, SD card and other storage media. The free edition of Data Recovery Wizard can recover 1 GB files free of charge.
It works under Windows 2000, 2003, XP, Vista, 2008 and 7, it fully support Windows 7 SP1 and Windows Server 2008 R2 SP1.
Total Recall 1.1
Total Recall is fully equiped to restore deleted or lost files from hard drive, removable memory, optical disks (CD and DVD) and even deleted emails if the user's email client is Mozilla Thunderbird or Microsoft Outlook, its user interface is practical and well designed. The publisher says that Total Recall "can recover just about anything that is normally mountable with a drive letter. It ever recovers Mac HFS/HFS+ volumes from Windows."
Bad stuff: can't restore files from an unbootable hard drive.
Handy Recovery 5
As the name suggests, Handy Recovery is practical and convenient data recovery program. Using this software the user can browse the conent of the disk like he does it in Windows Explorer, the only difference is that the user can see the deleted files and folders along with the regular undeleted ones. The program can search for files by name, can mask and show the probability of successful recovery for each file. The recovered files can be saved to any accesible disk. The user can also restore the full branch of folder tree containing selected files and folders. The program can recover alternate data streams used on NTFS file system to store additional information about files.
It works under Microsoft Windows 9x, Millenium, NT, 200, XP, 2003, Vista and Windows 7, it supports all Windows file systems for hard drive and floppy drives including FAT12/16/32/64(ExFAT), NTFS/NTFS 5 and image recovery from CompactFlash, SmartMedia, MultiMedia and Secure Digital cards. It can recover compressed and encrypted files on NTFS drives.