I had a hard disk that was fully encrypted as a system drive with True Crypt 7.0. After a sudden BSOD, Windows system failed to start: after password entered, TC gave message "No bootable partitions found". I tried to just decrypt the whole drive with use of True Crypt Rescue Disk, but it seems very slow (nearly week). So, I tried another way: boot a "live CD" system and mount drive as an external, using option "Mount without pre-boot authentication", but TC failed to mount it, giving me a message "Error: The process of encryption of the partition/drive has not been completed. It must be completed first."
I think the quickest way is to re-encrypt decrypted area, but I can't understand how to do that. Is there a good way to do it?