Sony Vaio stuck in MS DOS boot mode

I have a very old Sony Vaio Notebook (PCG-9231) running Windows 98. I decided to re-start it in "MS DOS" mode just to see if I could troubleshoot some OS glitches (I have no idea what i'm doing just so you know, I'm a Mac person) and now it's STUCK in "MS DOS" mode (guess thats what it's called) Just text and commands only. I've been able to bring up the "BIOS Setup Utility" by holding down F2 but no matter what I do I cannot get it to boot normally back in Windows 98.
What the heck do I do?


Thanks for any suggestions