PLEASE, PLEASE, READ EVERYTHING FIRST. I DO NOT WANT TO BE RESPONSIBLE FOR SEVERE DATA LOSS. IF YOU FEEL UNCOMFORTABLE WITH MY APPROACH, DON'T ADVENTURE YOURSELF.
Assuming that you have backed-up everything that is on your laptop, I would follow the following steps. Make sure your read everything clearly before proceeding. This might result in an unstable Windows installation. I have a couple of suggestions to make.
1) The first time I wasn't able to boot anything (Ubuntu and the USB pendrive) but Windows, I booted back to Windows and formated my USB to FAT32. If in doubt, use different USB drives (not all of them allow Ubuntu as a live system), if possible. Try to boot again after using the pendrive on windows. Also try uNetbootin, works everytime for me. If it is not working, you probably touched some "vital" settings in your BIOS (disk configuration, USB port allowing to boot from USB). Whenever you enter your BIOS, are you able to view your USB somewhere? (When you say that you are unable to boot on USB or Ubuntu, make your statement clearer).
If you are successful into booting Ubuntu from your USB, you could install it and WIPE your disk entirely THEN reinstall Windows IF, and only IF possible. If you don't know your BIOS activation key of Windows, search for software which will find it for you. IF you do not understand, do not proceed.
2) My second advice would be that you repartition your disk straight from Windows (as it won't allow you to touch to Windows partitions (OS, recovery,...)). Make sure you leave some unallocated space equal to the amount of space you want to use to install Ubuntu. If not done, create your USB first. If you have a CD drive, buys DVDs (it is ANNOYING but saves your from so much trouble. I have lot's of experience when it comes to installing Ubuntu in the cleanest way possible) and burn DVDs of Ubuntu images. Boot from either the UBS or the DVD, and proceed with the installation. Now, this is when the hardest part comes in: selecting your installation mode.
When you arrive to a step when you have to choose between ERASING your disk and SOMETHING ELSE, choose SOMETHING ELSE. Then, recognize the unallocated space you created in Windows. Create and ext4 file system out of it, format it (again :) and mount it as "/". If you want to add swap, add it. Add anything else you want to. Also! This is important if you boot in UEFI mode (USB or DVD). Make sure you have your efi partition on (the same used by Windows). Don't delete it! Don't format it, use it as EFI partition!
Install Ubuntu and you should be safe.
3) Final solution. Throw all of you important data somewhere safe, WIPE your disk while installing Ubuntu and don't bother risking a Windows recovery partition's life!
In the worst case scenarios:
You still can't boot from neither your USB/DVD/Ubuntu fresh install. That means you played in your BIOS;
You didn't play in the BIOS, you don't have a CD drive: ask a friend for a USB drive that works well;
Buy a cheap USB at least having 2GB of space storage.
If you still can't install Ubuntu, explain everything you observe while/as you try to install so it'll be easier to track down. Good luck!
