E-discovery firms, unlike firms involved in the traditional discovery process, make use of electronically stored information in court cases. Litigants are required to exchange relevant documents in a format that is allowed by the court. One issue that often comes up when doing a search for discoverable documents is whether it is possible to recover documents that have been deleted. When dealing with paper documents deletion is a serious problem since once they are put in the trash or recycled, getting them back is close to impossible. However, for electronic data, there are some ways to recover information even if it has been deleted. 

The easiest way to recover deleted documents is to see whether or not a backup copy exists. Many organizations make automatic backups of their data storage systems on a regular basis. This means that even if the needed documents are deleted from the active disk, they may still be available on backup media. 

If no backup exists, things get a bit more complicated but they're usually not hopeless. It all comes down to how long ago the data was deleted. Most PC and server file systems don't actually “delete” any data from the drive when a user deletes it in the operating system. The files are simply hidden from view and space is marked as “available” on the hard drive. However, the zeros and ones that compose digital data are still physically on the disk. Assuming that the specific area of the disk where the files were located wasn't overwritten the data can still be located. There are many free and paid tools that allow for the recovery of deleted files. Even if the files were overwritten, it may still be possible to retrieve the file partially. A completely overwritten file, or a disk that has been physically damaged, may still contain recoverable data. However, finding this data would involve sending the actual storage device (or what's left of it) to a service provider specialized in computer forensics to see if anything can be found. If a drive has suffered severe physical damage, such as by someone taking a sledgehammer to it, data recovery may take months and cost several thousands of dollars. 

Mobile devices work in a similar way. Just because a user may have deleted a certain piece of information, or even done a “master reset” of the device doesn't mean the data is physically gone. There are some software tools which are specifically designed to examine mobile devices in an attempt to recover data. If this fails, or if the device is physically damaged and cannot function on its own, it may be sent for inspection to a lab that specializes in data recovery from mobile devices. However, it should always be known that recovery is never guaranteed and files that are recovered may be corrupted or have sections of their data missing.