What exercises can i do?

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So basically. I had an ectopic pregnancy and they gave me methotrexate (cancer drug) they said no eating healthy or excersizing for 4 weeks. so after 4 weeks i worked out. my first day working out i was doing the wii and i twisted wrong and heard this low pop pop pop pop pop. I then fell to the floor unable to get up. I tried to get up a bit later more popping in my knee and horrible pain. ER said I sprained my knee( only did an xray not and mri)...i have all the symptoms of a torn ligament....

ANYWAYS, i am in a wheel chair but use crutches when i have too (hurt my other knee and back). Its been 3 weeks i can bend my knee. i just cant put my full weight on it...

Is there any excersizes i can do for weightloss in a wheel chair or in bed?? im losing weight dieting but i need to be exercising im going crazy!