Jenny, perhaps you're thirsty ? Have you tried drinking a couple of glasses of water ? Some times hunger isn't really hunger, but thirst.
Also, is this the normal time you'd be eating lunch ? If so, your stomach might be expecting food that you're not giving it. Learning your body's signals isn't easy. It takes time. Personally, I prefer to keep my body on a schedule. I find that when I don't eat a certain intervals, I end up ravenous later. So, I try to keep my meals and snacks on a regular schedule.
If you don't want to eat, you need something to keep you busy. If you're at home, how about cleaning up the kitchen ? vacuum the rugs. dust the tables and counters. When a person is busy, they don't think about food. Try to keep busy if you don't want to eat. BUT, if you are genuinely hungry, have some fruit or have lunch if you haven't eaten yet. you don't have to starve yourself to be healthy.