Plants Dieing Of Very Suddlenly

[civicr]

i have alot of java fern in my tank and over the past week there turung brown an the leaves just fall off theres hardly any green healthy jave left my ligh tin the tank is currently on7 hours a day there not bewen any change to my tank.its just happend ive done a water change but it hasnt made a diffrence.does any 1 think i could do with replaceing the lamps in my hood?

 

[Christine1014]

Java ferns don't need much light, so I'd do a little more investigating before doing anything potentially expensive.
Are your java ferns tied to a rock or piece of wood, or are they planted directly in the substrate? If they're planted, that's likely the problem. The rhyzome (that sort of bulbous thing at the end where you'd see roots on other types of plants) can't be buried or it will rot, killing your plant. If you're javas are tied to something, are you giving them any kind of fertilizer?