Just a thought toshiba sucks. ive had two of them and my old one is still running after a screen replace 2 times. that from 2005 my newer one from 2010 is on its second hard drive and the mother board just took a crap after the hard drive crashed last year and the power plug was always loose. I used to like toshiba but now im with HP. Sorry.
anyway im not expert i assume you dont have a boot disc to boot from..
without looking it up cause i dont have time but reboot it and keep presssing f8 or f2 if that doesnt work. get into the bios screen make sure you are booting from your hard drive that should not have changed should be your c: drive. if all that is set up make sure check things out if you can get into safe mode select windows normal mode. and also when u are in the bios you will see a tab called boot which i what i was speaking of above. check that out and drop down tab make sure your booting from your hard drive where your boot image is located.