When you delete a file permanently or empty the Recycle Bin, the file stays in your hard disk until space it allocated is overwritten with new data. Basically, all Windows does is it removes the first character from file name and removes it from FAT, File Allocation Table
, thus making the file "invisible" to Windows.
Undelete, unformat and file recovery tools can find these files, normally showing a $-sign replacing the first character.
There are only two ways to be sure a file is completely wiped from disk:
- a disk reinitialization, often misleadingly called Low-Level Format or LLF
- repeatedly overwriting the space deleted file allocated, normally done with so called file shredders (here's a free one: File Shredder)
So to answer your question: yes, it is possible to tech support to "dig out" your sensitive, deleted data if it is not effectively overwritten or the disk is not reinitialized.