Firstly, thank you for your help.
I am using a dell laptop, however when I am in advanced boot mode it does not have a "repair your computer" option, so that doesn't help. It is a discontinued Dell (the inspiron duo) so it is possible it was made before this feature?
I have also moved my disk onto an empty memory stick - however whenever I try to boot from it, the screen just reads "missing operating system"
and I have already backed up all my files