Narrow Leaves Hygrophyla
That might be
http://www.plantedtank.net/forums/m..._Hygrophyla_Hygrophyla_corymbosa_angustifolia
If so you will be able to get two plants out of that broken plant if you give it enough time and light to grow. For the leafy part remove the bottom leaf or perhaps the bottom three leaves. You want to stick just enough stem in the substrate so that it doesn't float away. It should grow roots as the bottom portion did. -- For your bottom portion, trim away a good amount of that root and stick the stem into the substrate.
That might be
http://www.plantedtank.net/forums/m..._Hygrophyla_Hygrophyla_corymbosa_angustifolia
If so you will be able to get two plants out of that broken plant if you give it enough time and light to grow. For the leafy part remove the bottom leaf or perhaps the bottom three leaves. You want to stick just enough stem in the substrate so that it doesn't float away. It should grow roots as the bottom portion did. -- For your bottom portion, trim away a good amount of that root and stick the stem into the substrate.