I did the same thing, well actually the wind blew it off a picnic table while it was in a one gallon pot. In my case it was a known vigorous indeterminate hybrid (Bolseno.) The "stump" has sent up several new growth spurts and is doing great. I also rooted the top as insurance.

If your tomato plant is a determinate, I dont think it will work from the roots. But rooting the top sounds viable.

It is a Cherokee Purple so it is also a indeterminate but an heirloom. I think I will just leave the bottom half in the ground and hopefully I get lucky. Thanks.

As long as it is an indeterminate, it is virtually impossible to kill through physical damage. It will grow back very easily, it will just be bushier than before.

Also, if you want two plants, stick the broken top piece in the dirt. Don't even have to do anything special to it, just stick the broken bottom in wet dirt. It'll root and you'll have two plants.

When planting the top piece per Edymnion's advice, make sure the dirt stays evenly moist for three or four weeks, and try to shade it from strong afternoon light until it roots.