Hello Loner T and everyone,
I have a similar problem tried to increase the capacity of bootcamp from 100 GB to 180 GB and resized the Solid state from 400 GB to 320 GB and created a separate partition of 80 GB so i could merge the 80 GB into 100 GB bootcamp in windows 7. Once the partition is created i restarted mac and wanted to start windows 7 in bootcamp (which was normally in perfect order and had loads of important stuff inside too) but now it says " operating system is Missing"
which is very much annoying and i tried everything in googling but could not fix this issue and cannot get my windows 7 bootcamp. I can start mac and it works perfectly but bootcamp is missing operating system. I wanted to start windows startup repair in bootcamp and tried fn + f8 but it did not work and tried all f1 to f12 keys but nothing worked. can't go to windows startup repair at all, please help me how to fix my bootcamp windows 7.