physical existance of computer files..

As deshabhishek007, when you remove files from your computer, they're still on the disk, but marked so they can be overwritten. So when you format you PC, all the files are still there. The more new applications you then install, more previous (formatted) applications you overwrite. That's also why police can trace your files even when you formatted your disk few times over.

conservation law of energy : Energy can neither be created nor distroyed it can be tranfered from one form of energy to another. but in computer system, file's are not stored in any form of energy. when you create some file. the memory from harddisk is allocated. and the address of file is stored in file allocation table. now when you delete the file the address of the file from file allocation table is removed. not the whole file so only entry of file is removed from table. file exists in hard disk. you can access it by pointers. any Question?? Regards, Abhi