I've just installed Ubuntu 13.10 on my Acer AspireOne D255E alongside an old installation of Windows 8. After the Ubuntu install, I started Windows and Ubuntu without problems but suddenly I tried to start Windows 8 and it showed me a blue screen with a :( emoticon telling me that there was some troubles and windows couldn't start. I tried with the windows auto-repair but, as expected, it didn't work. Ubuntu is working very well but I need my old Windows 8 operative system and I don't know what to do to recover it. I'm a beginner using Ubuntu, so if you need any extra information, just tell me. Thanks in advance!
I'm not allowed to comment due to my reputation, so as an answer: Did you happen to change anything to your hardwareconfiguration? Added a harddisk/drive? Or maybe altered the order? Or maybe altered any order in your BIOS?
Those edits could change the order Grub (the bootloader, which handles your choice to boot to Win/Ubuntu) reads the drives and tells windows how to access them.
For instance: (HD0,0) could be labeled /dev/sda1 during instalation, while since altering something, (HD1,0) points to /dev/sda1 and (HD0,0) points to label /dev/sdb1)