you need a bootable cd or usb containing a Hard Disk Diagnostic Program to find out if hard disk is physically damaged.
The Seagate dos diagnostic disk is available as a ISO which you burn to CD using ImgBurn software
(this works to diagnose problems with any brand of hard disk)
If hard disk passes test maybe a emergency recovery CD will help or a Windows CD/DVD which is the same as your version of Windows will help repair corrupt system or boot files
XP/Vista/7/8 then 32 or 64 bit is important
(But Home / Pro / Ultimate is not important)
With modern Toshiba's (W 7) there are three partitions recovery & boot manager (hidden no drive letter)
, C: D:
(C: & D: are about the same size and each about half the disk size)
Did you make a recovery disk set for your Toshiba in case the hard is dying/dead ?