My period came today and i hadn't had it in a year i'm only 20 so i guess that wasn't normal that it stopped but now that it's back what does it mean?

Not ovulating: Your menstrual pattern suggests anovulation (you're not ovulating regularly). There are lots of potential causes: PCOS, thyroid disease, pregnancy. Check a home pregnancy test to be sure. It's not good for your health to go that long without a menses. Later in life that could put you at risk for uterine cancer. Please see your physician for evaluation and birth control pills (BCPs).