Exercise and weight loss?

okay there is not much I can do I have 2 spinal cord injuries one in the lumbar area. I had s1-L4 all fused and disks removed and continue to have pain and also have spurs there. my other spinal injury is in the cervical area and had c5-c6 fused and continue to have pain because the bone plug shifted. I can walk short distances other than that there is not much I can do. I have gained over 70 lbs in 4 years and really want to lose weight and firm back up any ideas for exercises?