My friend woke up one day not being able to use his left arm and is slowly losing his right, dr's at hospital don't kw what could be, any ideas?

Many possibilities: Possible causes include cervical spine stenosis, neurological disorders such as multiple sclerosis, gullain-barre or als, or muscular disorders such as polymyositis or statin-induced myositis. You should discuss the possible causes, appropriate lab and other tests, and treatment options with your friend's doctors. Or get a second opinion from other doctors.

Work up: Because symptoms are on both sides of the body, consider multiple (at least 2) lesions in the brain, a single lesion in the spinal cord if it is a nerve problem. Alternatively, there may be a problem with peripheral nerve or muscle. Start with brain and cervical MRI to rule out problems that require immediate neurosurgical treatment. If negative, neurology evaluation should be next.