I had an ultra sound scan on this month and noticed a cyst in left ovary. For the last 4 months I'm getting my period 4 or 7 days late. I don't have any unusual pain or disturbances any where. I heard that some of the cyst will affect the ability to ovulate. How may I know that I'm ovulating or not without visiting a doctor? And whether I will get pregnant or not?

Basal temperature monitoring. Google it. It will show you methods of estimating when you're ovulating. It is a guess like most methods but has some merit.

A cyst could hinder ovulation but you also have two ovaries. Whether you will get pregnant would be best left as a question to the doctor who will see your ultrasound scan. Many people will conceive with a cyst. Some won't and we don't know enough here to say which is which.