What can be done for a broken toe that was not splinted, now many years later it is humped and painful?

Not much: Way too much time has passed for a decent revision. Have your doctor refer you to a podiatrist.

Surgical correction: At this time, splitting this will not help. You will need surgical intervention at this time to correct the deformity if it hurts you. See a podiatrist and this can be fixed easily.

Surgery: Deformity is a frequent consequence of an untreated toe fracture. A podiatrist should be able to x-ray the toe to evaluate what is deformed and perform surgery to correct the deformity. The procedure is usually done in an out-patient facility and recovery time is minimal.