You need to boot your computer from a Windows installation disk or a Windows System Repair disk. With the former, boot to the installation screen and after choosing to install Windows you will then choose the recovery options to get to the Recovery Console and open a command prompt. Using the Windows System Repair disk boot directly to the repair console and then open the command prompt.
At the command prompt type:
bootrec /fixmgr<enter>
bootrec /fixboot<enter>
Exit the command prompt, quit the Repair Console and boot your computer normally. It should boot properly now. If it still gives you errors then you should try some data recovery software such as Recuva by Piriform or EaseUS's Data Recovery Wizard or any other of a number of such programs with great reputations.