After 2.5 yrs. of leg numbness & pain, i have diagnosis of meralgia paresthetica. what are common treatments & likelihood of success after so long?

Pinched Nerve: Meralgia paresthetica is a pinched nerve syndrome. If conservative care and injections don't help you may have a pinched nerve in your back. I would suggest seeing a pain/spine specialist to evaluate you further to evaluate what level and what can be done to treat you. There are interventional treatments besides medications and surgeries that might reduce or eliminate the pain altogether.

2nd look: Meralgia paresthetica is burning pain and numb feeling in the outside and front of thigh i.E pant pocket area. Usually it resolves after about 6 months and putatively occurs by a pinching or disease of a nerve called lateral cutaneous nerve of thigh. The duration of symptoms raises some doubt about diagnosis. Also if by "leg" you mean some other area than thigh then also doubt is raised.