If you did have NPD, this is what psychcentral has to say about treatment:

Narcissistic Personality Disorder Treatment | Psych Central

I was diagnosed with PDNOS -- personality disorder not otherwise specified. So if you're willing to consider the possibility that you might have a personality disorder, and you want to do something to change that, then I'd recommend that you try to find a therapist who specializes in personality disorders and go for a consultation and evaluation. Treating this stuff ain't easy, but it can be done by people who know what they're doing and have done a lot of their own therapy, to minimize the risk that their own stuff could interact with yours in an unhealthy way.

Is there anything else that you would like to ask?