The sooner you start running a data recovery program, the better your chances of recovery will be. However, even if it’s been a little while since you discovered your missing data, all is not lost: even if a file has been overwritten once, it may still be salvaged by an intelligent data recovery program.
One of the ways that bad guys are able to get your personal information is through the use of computers that have been disposed of. People will throw away their computers without erasing their data off of it. They think that they are not important enough and that no one will dig in the trash can for it.