Been sick/also injured knee

Hi, I've injured my knee and saw a dr. He said to not use my elliptical anymore, no squats Etc until it's feeling much better. Still hurts when and after I work out. I haven't been working out much cause of this-
Plus I've been sick. I was doing really well- now needing a lot of encouragement and support to get back to it. I've been depressed... I also am not sure what exercises to do with my knee. Any workout advice? Or diet advice? Also I want to be down to 119, in 131.4 now, 5'3. But lacking muscle tone, and need to know how to best utilize my workout time since I stay home with two one year olds. Thank you!!!