I don't know a lot about Linux, but how did you set up the boot originally, and have you changed the drive order in the bios or disconnected and reconnected a drive so as to cause the order to be changed?
I originally plugged Linux into a cd/dvd cable(I have no idea how) then I asked my older brother who set it up on another pc, I gave that pc to my little brother as i got another one and took my linux drive with me. any way he told me i had it plugged into the wrong cable so i plugged it into the same one my main hard drive(WIN7) was plugged into. I then went into bios set windows as slave and linux as master.
It sound like the bootloader doesn't have Linux as an option to boot to.
Try downloading and running EasyBCD.
You can use the Add tab to add Linux as a bootable option and put it first in the boot sequence and give to give you a boot menu.
You can decide how long you want the computer to wait before going ahead with the boot, what to beet to etc.
It worked and i could go to windows 7 and linux but when i booted to linux i get a black screen with a white blinking bar like it's about to type something except it doesn't.
Could this be because my linux hard drive was wiped of it's OS?
That normally happens because the boot is not seeing the OS. Try using EasyBCD again and see which partition/drive it is pointing to. The NeoSmart Technologies site has a Wiki that goes through many scenarios.