My pregnancy should been 11 or 12 week, but through the scan it show that it only 7 week. The doc say that he cannot see the fetus as he expected.there is no heartbeat and no pic of it.I'm so worried about this after my doc tell my to wait another 2 week to see whether my period will come or he will clean my womb.he say that my baby cell is a sick cell so that my body cannot let the baby to grow.

Has it been 11 or 12 weeks since your last period? Is this how you are dating your pregnancy?
It would be unusual not to see the fetus at this stage but perhaps dates are off a bit. When you have another scan in 2 weeks, you will be better able to determine the situation.
Wishing you well.