Hello Johnny there might be no need to format you HDD there is still some hope for your Windows 7 installation. Hoping that you have a working DVD ROM. Use your Windows repair disk and this should do the trick! The problem with your installation is that your boot MGR might have been corrupted the Windows repair disk will most probably do the trick. If you do not posses one ask your friends but most probably you PC Manufacturer gave you one. If all else fails then try this
Restoring Windows MBR without a Windows CD
If you want to boot directly to Windows but Grub has overwritten the MBR, the normal procdeure is to use the Windows CD to restore things. If you do not have access to the Windows CD, the following commands will rewrite the MBR, removing Grub and allowing the system to boot directly into Windows.
Boot the Ubuntu LiveCD, open a terminal (Applications, Accessories, Terminal) and enter the following commands. Make sure you correctly identify the Windows device (normally sda):
sudo apt-get install lilo
sudo lilo -M /dev/sda mbr
Note *You will lose the option of booting into Ubuntu* so if you do not want to do this I suggest you follow the instructions on this page How to restore the Ubuntu/XP/Vista/7 bootloader
Hope all this works!