Windows 7: Win7 won't start after full installation (followed by Win8 install)

So I tried installing Windows 8 on my Novatech Laptop, having windows 7 installed on it previously. I deleted the 7 partition and installed 8. It booted, but hung right after booting into hdd. Then I decided I don't need 8 and tried to come back to 7. There where a couple of problems with creating partitions on my hdd (while using clean windows install disk), so i just formated it all (low level format using some hirens boot cd tool). After that i can create partitions from 7 installation disk, and install windows 7, even restart the laptop once during the installation, boot tino hdd and continue the installation. After installation is over the computer just keeps restarting and won't boot .

Where did you get Windows 7 installer? Did you burn the DVD yourself? If it's been used successfully before does it now have scratches or smudges? If so try cleaning. If not try a new official ISO burned with the tool in Steps 1 and 2 of Clean Reinstall - Factory OEM Windows 7.

Boot the installer, at first screen after booted press Shift + F10 to open a Command Line to run Diskpart Clean Command, then close Command Box, click Install Now to Clean Install Windows 7.

If this fails try entering Device Manager during install to disable any erroring device so install will complete: Device Manager - Access During Windows 7 Installation

tried all you said. The windows gets intalled but then wont boot, at all, so when i press f8 to choose safe mode, the computer keeps rertarting. It is interesting that i dont have any problem with xp, but even if i try to boot live windows 7, it fails to boot, it says BlInitializeLibrary failed at 0xc0000017

This error occurred after wiping the HD with at least Diskpart Clean Command and trying another installer ISO?

Test your hardware and run a few Startup Repairs after confirming Windows 7 partition is marked Active from Troubleshooting Windows 7 Failure to Boot

Try Clear CMOS - 3 Ways to Clear the CMOS - Reset BIOS then set SATA controller to AHCI to reinstall.