Hello user!
Please go to droidboot mode(the tutorial link:http://www.asus.com/zentalk/forum.php?mod=viewthread&tid=5564) and factory reset your phone.Since it is a security issue,all your data will be lost.
If you don't want your data to be lost,please visit nearest ASUS servicing centre with all your details of purchase and the payment bill.keep imei no. handy.
They will solve the problem.