There's probably a Windows.old folder in your C: drive that has all of your Windows 7 files/programs/backups if you did not delete it. That's what would happen if you chose not to "delete" Windows 7 when installing Windows 8. Windows 7 is not bootable at this point.
Edit: It is possible to restore your Windows 7 from the Windows.old if you still have it. It is also possible to roll back and dual boot from Windows 7 and add on 8 with partitions.