TestDisk is an advanced free recovery tool designed for IT professionals. Working under General Public License, this app has been considerably improved over the years and it can now recover lost partitions and make bootable disks out of non-booting disks.
Obviously, this will happen only if the errors are caused by a faulty software, viruses or human interfering. Additional features include FAT32 boot sector recovery, FAT tables fixing, NTFS boot sector rebuilding and mirroring.
If you are not an experienced user or technician, you may choose to collect detailed information on the problem by the use of this tool and send it via e-mail to a friend.