I cannot boot my Toshiba laptop at all

[wailfayez]

my laptop is Toshiba L755-16H, windows 8.1 update
All what I get now is a a first screen of “Toshiba Leaading Innovation” and “H2O bios” then the logo of windows 8 (4 blue quartered window) then black screen with flashing cursor and keep like that.
The details as follows:
it was working normally until certain critical update from Windows update, then it refuses to start at all.
in the beginning i tried to get into recovery options> advanced options> repair start up> but no benefit.
then i tried system restore> it failed and no benefit.
then system refresh> but i have windows 8 dvd not 8.1 so it said not suitable cd
the i searched the internet to enable safe mood and entered the command in command prompt
“bcdedit /set {default} bootmenupolicy legacy” (no quotes) from this forum:
http/www.bleepingcomputer.com/forums/t/525027/windows-81-wont-boot-cant-access-anything/
and I could get into safe mood and tried to do system restore but it also failed.
After that I couldn’t boot the computer at all or even get into the system BIOS setup with F2 or F8 or F12
Also I tried to enter the dvd of the Recovery or the dvd of windows 8 but the they spins for little seconds and nothing happens although I am sure the dvd rom is the first in booting sequence.
I tried to disconnect the power supply and remove the battery then press the power button for 2 minutes > but no benefit.
I tried to press 0 (zero) with the power button on starting up and keep pressing zero to go tto factory settings but no benefit.

 

[wailfayez]

RESOLVED

Thanks God, and Thanks sincerely for every one tried to help me.
Nearly the problem has been RESOLVED
I think it was a matter of corrupted Master File Table (MFT) and volume bitmap and also Malware detected.

Here you are the details:
I removed the HDD from the defected laptop, and connected it to a SATA enclosure and connected it via USB cable to another working laptop.
I have performed a scan with antivirus (360 Internet security) but I didn’t leave it to finish. It has detected a Trojan in the following path ” \Program files (x86)\Toshiba\Bluetooth Toshiba Stack\LANG\PTB\BTAssist.chm” detected as Advanced Level Trojan Program.
I believed it may a problem of corrupted Registry or File system, so I have performed Error checking for the Windows partition (from Properties of the desired partition the Tools tab then “Check” under Error checking section, it found some errors and fixed them . then I stopped the antivirus scanning, connected the HDD and tried booting but no improvement.
I believe that that way of error checking is not very effective and the better method is via the command prompt so I opened cmd , then entered ( chkdsk driveletter: / r ) then it found many errors in the MFT and volume Bitmap (I am attaching a file containing the result). It corrected the errors.
I removed the HDD and connected it, and WOW the option to enter BIOS via F2 and boot sequence via F12 returned as a bottom line, and I could enter BIOS setup.
As I mentioned before my laptop doesn’t have UEFI as I entered the BIOS setup and didn’t find the Secure boot option.
I make the boot sequence DVD > then USB > then HDD.
I loaded Kaspersky Rescue Disk from a USB and did basic scan on just the start up items and memory it didn’t find anything.
Still windows refuse to load normally.
But I could boot successfully from live CDs like Hiren’s boot and checked the memory, it was ok.
- I burnt a new DVD of windows 8 as the one I have may be slightly scratched so the lap couldn’t from it.
- And finally I could boot from the windows 8 DVD, and tried to fix the start up> it failed.
- I tried to do system restore > failed
- I tried Refresh system > failed
- I tried Reset system > failed
So I decided to install a fresh copy of the windows.
And yes I could boot and went through installing a fresh copy of Windows 8 after FORMATTING C drive. And it went very well.
Now the windows is working very well. And I am performing another ( CHKDSK c: /r ) to make sure of the HDD.
It has finished with no errors detected and 0 KB in Bad sectors, Thanks God.
And till now everything seems very well..
Thanks again very much for every one tried to help me.