I'm not entirely sure how i messed up bootmgr but i did and it was something to do with a dual boot ubuntu install. Basically: if I have my c: and my d: drive in my pc, windows can boot absolutely fine. Stick in the f: drive, windows won't boot. It displays error ocx000000f. My theory is that boot manager has instruction somewhere in one of my drives (only c or f though) to try to boot to windows in the f drive, although there isn't a windows installation there. Please tell me what you think and if you think i'm close to being right, I may be able to fix it if i can rebuild the bcd, but I can't get to command prompt ANYWHERE. It displays an error along the lines of 'your Version of windows is not compatible with the disc' ( even though it is the exact disc used to install windows in the first place and yes i checked) I can't use advanced options. Is there any other way to get into command prompt OR would it be possible to stop windows from recognising it as the drive it has to boot from without reformatting, if i didn't have important files in there, i would just reformat and/or and buy an ssd. Thanks.