Can Overwritten Data on a Drive Make Older Data Unrecoverable?

Don't think that deleting files from your hard drive destroys them; files do not disappear immediately when you empty your Recycle Bin. In fact, you can format your hard drive and it may still be possible for someone else to recover some of its information. If you want to make older hard drive data unrecoverable, use specialized software that overwrites the space on the hard drive.

When you need to recover files you've deleted but not overwritten, use a program such as Orion. It can help you search for files to recover on memory cards, USB drives and regular hard drives. If you'd like to overwrite a file to make it unrecoverable, you can do that too. Eraser and Piriform's Recuva also recover deleted files and overwrite those you want to disappear forever. Recuva comes in a desktop version and a portable version you can take wherever you go.

Windows 8 introduced File History, an automated system that copies personal files that change to external storage devices. Personal files are files such as the ones that reside on the desktop in libraries and in your contacts folders. You must configure File History before it backs up your files automatically. The restore application helps you restore a file that you deleted or lost. Restoration is possible if you overwrite an existing file because a copy of that file exists in an external location.

In 2003, two MIT students bought 158 used hard drives. Only 12 drives were cleaned properly; the students discovered more than 5,000 credit card numbers and other personal information on the rest. If you're going to sell a computer or recycle it, use a program to overwrite your hard drive to ensure that the new owners cannot restore your files. If you work with documents, images or multimedia files that you'd like to remain confidential, it's also a good idea to make those those types of files unrecoverable after you delete them.

When you save a file on your hard drive, Windows breaks the file into segments and stores those segments in different locations on the hard drive. The operating system reassembles those pieces to recreate your file when you open it. Deleting a file simply gets rid of the links Windows needs to reconstruct the file. The actual data still exists, which is why recovery software can put a file back together. The Federal Trade Commission recommends using a program that overwrites a hard drive several times if you want to ensure that nobody else can recover your files. Some software programs may only overwrite files once.