Because you stopped it part way through the process, you're pretty much going to have to reinstall Windows regardless. As far as your data goes, RunLuke's suggestion of using an external drive bay/enclosure is probably going to be the easiest way to save it. If you don't have one already, they are pretty cheap (most can be had for about $20-30 if you're in North America). Connect the enclosure with your hard drive inside to another computer and move all of your data to it temporarily. When everything you need is copied over, remove the drive and put it back into your computer. Reinstall Windows.
Once Windows is up and running again, you can either remove your drive from the computer again, put it back in the enclosure and connect that to the other computer storing your data so you can copy it back. Or you can create a network share on either system, connect to it from the other computer, and copy all of your data back over the internal network (though this option depends on both computer computers being on the same network.