Why now is computer go from off to toshiba back n fourth and fast

[Patriciaaa]

I got it into f12 and it shows Lan with a red exclamation their is no partician on hdd it wont boot up screen flashes toshiba then blank screen what do i do? Plz help btw i have a toshiba L675 satellite

 

[Saga Lout]

It seems that the hard drive has failed and the partition that is missing is the one Windows needs to read to be able to run properly, or at all. It's odd that you can see a LAN warning because that would only show when Windows was starting up.

With that confusion and the need to have equipment to fix it, your best shot would be to take it to a professinoal PC Fixer, They can remove the hard disk and slave it to another computer, recover your personaal files and hopefully, fix the lost partition.