I've not had periods for 2 months urine and blood test negative for pregnancy what cud b the reason4 not having a period?

Many things: Something as mundane as too much stress can release hormones that interfere with normal cycling; if you have gained weight, you may have irregular periods; certain medications can cause prolonged intervals between cycles; polycystic ovary disease, etc. So, while I am not saying you have any of these, pregnancy is not the only cause of missed periods.