Thanks for you answer, actually I´m getting the larger problem - I can´t load even BIOS, so no safe mod possible. When I turn my computer, there are just few lines with text and "Please insert boot disc and press any key" Not a word about Microsoft or anything, no BIOS.
This means it does not see your HDD. I think BIOS should be OK.
When the machine boots you have 5-8 second message to select a function key to go into BIOS.
It depends on your machine...but sometimes DELETE key, sometimes F2.....it should show on screen.
Once in BIOS go to main page that shows HDD.....see if it lists the HDD....usually in the menu that has the boot devices.
If the HDD is "listed" then the HDD has not crashed....should show manufacturer/size, etc.
If the "HDD" is "not listed then the HDD has crashed......bummer.....hardware failure.
If this is the case then if you are not a techy you need to bring to PC shop and have them pull the HDD out of the laptop and hopefully access it via external USB control and pull your data files. If so, then they will need to put in new HDD, install O/S, etc.
If the HDD
IS listed in the BIOS then the hardware has not crashed but the boot sector does not know where to find the O/S.
At this point go above to my comments and see if you can get a repair Windows 8 repair CD and boot to it...perhaps it can "repair" the issue.
If you are up and running in the repair CD there are other options within the command prompt you can get to try to get to known last good point on restore point. However, at this point I'd go to the MS forum and start a post/thread there to have them help you on restore.
Question, at the beginning of this topic you said your battery went dead ?......are you sure ?
You were running on battery alone ?......not plugged in ?
I ask because if you were on AC power then even if the battery died the laptop would not crash.....thus, sounds like a HDD crash.
If you were 100% on battery then if you were "running Avast" that means you were booted...you said that you crashed during O/S boot.
So, I'm confused when the crash really happened, what you were doing, and if you were plugged into AC or not ?