Not wonderfully sure about this, but here goes anyway.
By using FDISK, you have wiped everything on the drive - I assume you knew that beforehand and meant to do it or accidently put the wrong parameters in. That includes the bit which provides the DOS prompt.
What I hope you have done is made a boot floppy, which contains the bare bones of DOS, which is normally enough to get you going again in cases of emergency.
Or, if you have the Windows disks handy, you could just reinstall. Which you'll need to do anyway - or at least just install an operating system. Remember to go into the BIOS and set the boot order appropriately.