I have cronic knee pain after an accident. The MRI and X-ray results are negative. What can I do to help it without drugs?

Aquatics/acupuncture. Injuries after accidents can unfortunately lead to chronic pain (despite normal imaging tests). It's best to stay active, work with a physical therapist to maintain your strength. Consider aquatic therapy as warm water combined with non impact strengthening can be therapeutic. Alternative treatments i.e. Acupuncture may be beneficial. Consider seeing a pain md for further recommendations.
Many options. Physical therapy, and some of their modalities like a tens unit and ultrasound. Brace or even just a knee compression sleeve can help. Topical rubs like biofreeze, tiger balm, etc. Accupuncture.