To me it sounds like data recovery is needed. Yes you may have to use software, a recovery house or if you planned for this, your backup copy.
when i was formatting C disk during instalation of windows XP the electricity was gone. After that I turned on computer and went into windows instalation tab, all the disks were unioned in one big disk. now I want to restor all the data from HHD, but with all folders and file names, is it posible to enter to the HDD without any data recovery program?