I'm having trouble deciphering what is going on. Did you just upgrade to 7 from Vista? Did you just flash your BIOS willy nilly?

If your BIOS was reset you may need to tell it what your primary drive is - that may be why it is not detecting your HDD.

And for future notice -- Back up your data before you do ANYTHING involving flashing your BIOS, major OS upgrades, etc.. you should have it backed up, regardless, due to the fact that hard drives fail without warning. If your operating system is hosed you may still be able to retrieve your files (using a liveCD or something) but afterwards you're going to need to reformat.