Files may get deleted in two different ways i.e. one is by using Shift+Del keys and another by using Windows explorer. In Windows Operating system, when the files are deleted using Windows explorer, they are generally moved to Windows Recycle Bin. Later, if you want those files back then you can restore them from Recycle Bin. Recycle Bin stores files and folders, which are marked for deletion. But, when the files are deleted using Shift+Del keys, they are not moved to Recycle Bin instead they bypasses the recycle Bin. If you have accidentally deleted the files using Shift+Del keys then you cannot restore them from Recycle Bin resulting in loss of files. If you want to recover deleted files, then you need to use relevant file recovery tool.
Generally, when you delete a file, the Operating system does not really erase the file from hard drive. Operating system just marks the file name in file allocation table with a special character, which tells the processor that the file has been deleted. Actually, Operating system replaces the first letter of deleted file with hex byte code i.e. E5h that specifies that the file has been deleted. Sometimes, you may accidentally empty the Recycle Bin resulting in loss of files. In general, hard drive stores files in non-contiguous manner. For instance, if you are storing large file then that file is not stored in contiguous locations instead it stores that file in free available locations even though they are widely separated on the hard disk. When the file is fragmented in this way, hard drive takes more time to access each individual part of file for use. Therefore, you need to defragment the disk in order to improve the performance. While defragmenting, if sudden power failure occurs or if you accidentally turn off your computer then files may get lost.
Always, take backup before defragmenting your hard disk to avoid loss of files. In general, when the files are deleted, file system marks that space as available for storing new files. Therefore, when you save or copy any new files over an affected hard drive may overwrite the old files resulting in permanent loss of files beyond the recovery. Make use of UPS to avoid power failure problems. While deleting make sure that the file you are deleting is not important to you. If you have not taken backup then use relevant recovery tool to recover accidentally deleted files from hard drive.
Remo Recover (Windows) Basic Edition recovers files that are accidentally deleted or lost from hard drive. This software supports different types of hard drives like SATA, SCSI and IDE manufactured by different manufacturers like Seagate, Western Digital, Samsung, Hitachi etc. This software also recovers files that are emptied from Recycle Bin. This software has an ability to recognise and reciver different types of files based on their unique signature. This software supports recovery of files from different types of file systems like FAT16, FAT32, NTFS, NTFS5 and ExFAT. You can download free demo version, where you can view list of recovered files. Later, recovered files can be stored on any accessible drives of Windows.