Please help, severe knee pain, shaky when standing or trying to stand. Was at bedrest long time. Can I get strong?

Why the bed rest. Begin in water work with therapists wieghtassisted treadmill works people have madevit backto marathons-after brain stem strokes i doubt if your as bad off since you can communicate with computer.
Evalaute, rehabilita. Need to know why you have knee pain. The examination, imaging like x-ray, ultrasound, MRI and laboratory can help. If you have been at bedrest for a long time - consider very intensive physical therapy. You may have lost a lot of knee muscle tone like the quadriceps. I tell patients there is the "2 for" rule. For every day you are out, it will take 2 days to return. Get to work.