What type of file is it? If it is one of the following: jpg,gif,png,bmp,avi,exe,mpg,wav,riff,wmv,mov,pdf,ole,
doc,zip,rar,htm,cpp then you might want to try
foremost.
Mepis probably has it prepackaged but it is more sensible to run it from a live cd.
Code:
# foremost -vT -t filetype device
device can be the whole drive eg. /dev/hda Or if you know roughly where the file used to be you can select a partition. Be aware that the longer you have been using the drive, the likelyhood of retrieving the file intact decreases.