Does anyone know what is wrong with my plant
You have answered your own question when you wrote:
I keep it in my room, which is the basement of our house, and use fluorescent lighting in replace of sunglight.
Trees don't normally grow in basements under fluorescent lights. This may be appropriate for some species under some circumstances but it is never appropriate for a Juniper.
and how I can fix it???
It may not be "fixable" if it is indeed a Juniper it is probably already dead. By the time these trees dry out and drop their needles they are most likely expired, sorry. If it is any consolation it may have been dead before you received it. Junipers are known for looking reasonable long after they are gone.
On another front you have not mentioned how you have been watering it which is very important. Please pot a picture, use a third party hosting service and link to it here, this will help us identify it. In the meantime get it out of your basement and put it in a sheltered location that gets some sun in the morning and some shade in the afternoon. Make sure the soil does not truly dry out but do not over-water it either.
Please read the sticky threads at the top of the forum for basic care information.