I had periods two times last month. this month i didnt get periods yet. im worried about this. what can be the reason for this?

There can be many reason for the irregular periods. Sometime even stress can mess up your cycles. If you are sexually active, you may need to get tested to see if you might be pregnant. Otherwise, wait for another cycle to see if it will line itself out. If the irregular periods continue, you will need to be check for other medical conditions such as thyroid issues.