I installed Ubuntu on my Dell Latitude e6410 with Windows 7 already on it yesterday. I decided that the partition for Ubuntu was too big so i tried to resize the partion but i could not. Because i really hadnt did my much to Ubuntu i chose to unistall and reistall it and just change the partition size then. Following an online guide from askubuntu.com i delete the Ubuntu partition from Windows 7. I rebooted my laptop and to find the grub2 menu was giving me an error saying "unknown filesystem." My grub2 menu came up before the original bootmenu, i had to choose my windows partition from the grub menu in order to get to the bootmenu where i an choose from Windows 7 and system recovery (noob mistake im sure). I reinstalled ubuntu hoping that it would fix the grub menu but to no avail. I cannot boot to my Ubuntu installation, i have to boot from my usb flash drive so at the moment the only form of OS i have available is the "Try Ubuntu before installing" version of ubuntu. I also do not have a Windows installation CD/DVD so there is no chance of booting from that either. Helping with any of these problems would be fantastic.
1st: Ubuntu has a utility called gparted, use it to delete the partition with Ubuntu.
2nd: Let's try to fix your windows installation as this is probably the most important since it contains all your personal files. Pop in the your windows disk, and you'll be prompted to repair installation. You should be able to boot in Windows. Now you are back to a state before you attempted to install Ubuntu.
3rd: Use Ubuntu Live CD/USB. It'll detect your windows installation and ask if 1) You want to use Ubuntu (delete Windows) 2) Run Ubuntu alongside Windows 3) Advance (other). You'll want to choose option 2 (note: the actual option number may be different)
4th: After installation and reboot you'll be greeted with grub to boot into either Ubuntu or Windows.
EDIT: I just skimmed your post and missed the last sentence...would it be possible to borrow a Windows installation disc from a friend?