I know that there are several posts about operating system not found problem. But my situation is severe. My company will start to develop embedded systems on Linux at the end of this year and I wanted to get familiar with Linux.
I wanted to install Ubuntu 12.04. First, Ubuntu did not recognize windows partitions. I try to solve this problem (I do not know and remember what I did here but I think this is the problem). After several hours I manage to install Ubuntu on a 50 GB partition (in fact I think that I successfully install). After rebooting the computer, I see the screen OS not found. I realized that I cannot install Ubuntu properly and cannot boot from Windows 7 now. I use my Windows 7 disk to repair Windows 7 but installation cannot see any harddisk partition and cannot find anything to repair or re-install.
I am in a desperate situation since my work on my work computer is about to get lost. My boss is not happy with that and give me time to solve this problem by the end of this day.