How can I treat a prolapsed disc?

Thorough evaluation. Assuming you are referring to a herniated disc, start with your primary care physician to begin work up, order appropriate studies, and decide if you need a referral to a spine specialist (ortho or neuro spine surgeon). Not every disc herniation needs surgery - usually a last resort.
Varies. The treatment for a prolapsed or herniated disc can vary depending upon the severity of symptoms and whether there are any neurologic deficits. Most of the time physical therapy and specialized exercise will effectively treat most "prolapsed" disc.S surgery may be necessary for severe cases or large herniations with neurologic deficits and weakness.
See a specialist. A prolapsed disc (you did not specify where - your neck, your lower back?) may or may not produce any serious consequence. If the disc is impinging on a nerve root and causing pain, tingling, or worse, causing weakness of an extremity (arm or leg), then you need to see a neurologist first, and if necessary, he might refer you to a neurosurgeon.