Non-bootable device problem

Anyone can help me with the problem with my Toshiba laptop windows 8.1? 

My computer got too many downloads (Automatically)  I really hate that part because i only need very simple functions like email and internet news.  I was trying to restore to the factory default,  it didn't work. Then i was trying to delete some softwares , it didn't finish either. When i try to turn on computer again, it failed to start with error message says " Non-bootable device " .

I searched internet for solutions, followed a lot of people's sugestion, still not working.

Plus, i really hate windows 8 version.  Would like to change to windows 7 or windows xp. Is it possible to replace windows 8 with XP or 7? 

If anyone can help or have disk for solving this problem , i would pay for it and Appreciate very much.

Thanks