ok, nb member suggest me this script so i was install this script here.
but there are i am unable to login into admin pannel becaz captch not working.
then i start searching to solve this issue and reach at this site.
people post this same issue but solution is in other language. and also notice that phpGD create this problem.
then i was go to hosting support center and they said that this facility is enabled.
now let me know who can help me.