I think I am killing my houseplant! I'm not sure what kind of plant it is. I've been watering it weekly. There are leaves on the very top and new stems growing, but the leaves in the middle have all fallen. I remember that the tag that came with it said it needed full sun (which brings out the yellow spots, which is good), I'm not sure what to do to save it! It has a lot of sentimental value!
Your plant is a "Gold Dust Croton," Codiaeum variegatum, and it does look rather forlorn. The tag was right; crotons of all varieties demand the brightest light you can give them, short of direct, unfiltered sun. As for why your plant is dropping its lower leaves, there are several possibilites: It's simply not getting enough light It was recently purchased, and/or recently moved to a new location (this is both normal and temporary, and not necessarily a reflection of your botanical husbandry) You're drowning it-- although it's a thirsty species, the top inch or two of soil should dry out between waterings It has fallen victim to a spider mite infestation (check for fine webbing, or little dots that move when you shake the leaves) It's located close to an A/C vent. Plants dislike drafts as much as we do. The good news is, if you figure out the problem and manage to stop the leaf drop, you can just chop off the leafy tops of the plants and root them into new, healthy plants. See the method outlined at the bottom of this page.
Chanticleer that answer was right on the button especially regarding direct sun light, as most people assume that plants for indoors should not be in direct sunlight