Thyroid problem!!!

So I had a thyroid problem an I stopped taking my tablets for it as o didn't even no anythink about thyroid so I fort why am I taking these when I don't even no about it. But I had my bloods taken an my doctors have told me thay are not normal an I've got to start taking the tablets again. I just wanted to no if it can stop u ovulation as I didn't ovulate this an I'm also 5days late on my period but I'm not pregnant so can it stop your periods to ??