Certified GKH Gardening Expert
Do you have the cultural requirements for the plant? If it's tropical, it may be a full sun plant and not getting enough light. You can use grow lights or fluorescent if you aren't already. Or move it to a sunnier location like a room with south facing windows.
Also, it may be getting too much water. Most plants benefit from letting the soil dry between waterings. Then water till it runs out the bottom of the pot and remove any standing water. Do not let the soil be saturated.
If you think your plant is overwatered, then quickly repot in fresh soil. You may be able to save it.
My best advice is to find out the cultural needs of the plant and see where it is lacking. We probably have the plant on this site. Just do a search for the plant name.