I am 16 and cannot play m or t rated games what should i say to my parents aka mom to let me play them?

There is not much you can do. All you can do is inform her that a "T" rating is the equivalent of a PG-13 rating and that a "M" rating is the equivalent of a "R" rating. Are you able to watch "R" or "PG-13" movies? If so ask her how a "T" or "M" rated game is any different. Also inform her that they are mostly rated for language and violence, and that sex and nudity is a very rare thing in video games. (Often Americans see nudity and sex as some how worse then ripping out a guy's heart)