Eating some oatmeal for breakfast and maybe some other fruits such as apples and bananas would be a good 1,000 calorie diet.
For lunch or dinner maybe eat some salad and bread sticks and add in some yogurt if you like.
You might add some baked chicken to the salad but only a little bit of chicken.
Do consult with a doctor though to make sure that eating a 1,000 calories per day would be safe for you since for some people 1,000 calories only per day could be dangerous to your health.