Hi I'm having gluteal pain since last 4 years. Mri done & no problem diagnosed by doctor. Pl suggest solution. I can't sit due to this?

OMM. If an MRI didn't show anything specific then i would assume a musculoskeletal problem until proven otherwise. I would seek out a skilled do who uses osteopathic manipulation and see what they can do for you. I would specifically seek out someone who does omm almost exclusively as a specialist.
Sciatic nerve issue. Deep gluteal syndrome (dgs) involves compression of the sciatic nerve as it crosses under the piriformis muscle on the back of the hip. Common complaints include buttocks pain and a propensity to sit with the affected side raised up to avoid direct pressure over the area. In light of your normal MRI (presumably of the spine), dgs remains a real possibility. Specialized mr imaging is possible.