How to recover data from old unallocated hard disk

Hi, sunilkumar319!

Are you meaning that the hard disk isn't attached as part of a computer anymore or meaning something else, please?

Thanks!

Easeus should be able to help you

There is a free edition
Free Data Recovery Software to free recover deleted files and recover formatted or corrupt hard drives - EASEUS Data Recovery Wizard Free Edition. (http://www.easeus.com/datarecoverywizard/free-data-recovery-software.htm)

If does not help, depending on how important data may be, there are software you can purchase but no guarantee

Then can always format the drive and have the extra space