The boot menu or boot device menu would be an option separate from your main bios setup key. If you press F2 to enter the bios setup for things like the first drive in order or to set time and date, enable features another F key if the option is available will simply bring up a list of drive types to choose from.
If you have a pair of hard drives and press the hard drive item you then see both drives listed and have to choose one of them to boot from that. Likewise you will typically see CD, DVD as well as usb hard drive, card reader, etc. Once you select the optical drive and boot from that and later restart the bios takes over seeing the hard drive or other drive set as default take over again. You get a one time session each time you use the boot device menu option.
The sight of seeing the 7 logo screen and files loading must have been a relief to some extent since you are making some progress. Hopefully the optical drive itself is in good working order where you can get as far as the Install Now screen following the language and location screens setup starts with. Once you arrive at the large Install Now button look below that for a "Repair Tools" link.
When clicked on that will first detect any 7 installations and list what it finds on the first screen. From there you click the next button for another screen of options after first being asked if you want to restore a backup or image or run the system restore. You want the System Restore option to see any good points are still found while booted live.
If you are still forced into a clean install however note that Windows 7 as far as the Home Premium, Professional editions now offer the option to create a full system image you can restore to the main drive if needed. Backup Complete Computer - Create an Image Backup
That is stored on a second hard drive, removable media(several blank dvds for sure!), or a netwrok drive with Pro, Ultimate, Enterprisee editions. Vista first saw this only with the Ultimate not Business and HP editions there however.