Difficulty resizing windows partition to make a boot partition with large disk

I have a 3 TB hard drive and installed Ubuntu as a second operating system on my computer. I made the Ubuntu partition the final 300 GB on the drive. When I restarted, I got an error "attempt to read or write outside of disk 'hd0'" and neither operating system will boot. Googling, I leaed this can happen if grub is installed after the first 2 TB on a disk. (Side note- it's crazy to me that the Ubuntu installer doesn't check the disk size and give a waing and/or automatically perform a workaround). Then I found these instructions on how to Install Ubuntu on a large disk (https://help.ubuntu.com/community/In...buntuOnBigDisk). First I tried boot-repair, checking the 'out of disk' option, but it still wouldn't boot. The final option is to create a boot partition at the start of the hard drive. BUT the problem is that my Windows partition is at the start of the hard drive. I read online that I should not use gparted to move the windows partition (shifting it from the left, rather than resizing from the right). Trouble is, I do not have a Windows boot CD (just got a computer with an image) and so I caot boot into Windows and use the Windows partition tool. What can I do???