Need help, fridge is working, however the freezer isn't?

Came home from work and I noticed all inside the freezer department had thawed out. However the fridge is working fine. My Ariston fridge/freezer has a green light, orange and red light on it. The red light is continually on. I'm not sure of the model but there's a sticker on the back with ERFV 402 D ST on it. At the front there's a big strawberry and A.I.R at the top. It has 4 draws in the fridge section and 3 in the freezer . has anybody had the same problem, and if so how did you mend it