There is a terrific program called BootItNG from www.terabyteunlimited.com. It can solve a world of drive/partition problems in a flash. Also very easy to set up multi-boot environements on 1 or 2 drivers.
By having a second bootable partition, you virtually always can boot and see your existing data from a partition that no longer boots.
My PC is setup to boot about 11 different versions of windows from different drives/partitions. Very powerful setup and can be a life saver then main system quits booting.
