I format the hard disk and install a new os. can i able to recover the old files

47 is correct. Even if you scan the drive sector-by-sector, the OS install wrote to large parts of the disk, and the sectors that it wrote to, being overwritten with new data, cannot be recovered. There may be data lurking in currently-unused sectors, but your odds of recovering your files are not much better than winning the lottery.

Doesn't your format utility clearly specify in bold red letters that formatting a hard drive will cause all data to be erased, and that subsequently overwriting the formatted drive will cause permanent, unrecoverable data loss? Didn't it occur to you that you should perhaps backup your files before formatting?

Anyhow, there may be hope - typically the OS sets itself in the first available sectors of the drive (it doesn't just choose a location at random), hence if you installed only the OS after formatting, there may be hope of recovering your data, or at least some of it. First try and download some file recovery software (on a different hard drive, don't be stupid), and if that doesn't work then you can either give up or submit your hard drive to forensics, which should recover your data (again, maybe not all of it) with good probability but will also cost a lot of money.

No, quick formating alone will not permanently erase all data.
Installing an OS over top of a quick formated drive however will unfortunately overwright much of the drive making recovery unlikely.

Not really... as I said in my post, if the drive already had an OS installed (which it has since the OP mentioned he installed a "new" OS), then the new OS will overwrite the old one (because they all place themselves in the first HDD clusters), and perhaps a little bit of data if the new OS is larger than the old one. But he definitely didn't permanently lose all his data - he likely lost some, but not all of it.

What process exactly did you go through when you installed your OS, are you sure sure you formatted, can you check C:\ for a folder called windows.old just in case you think you formatted and did not format!

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