Welcome to DC Jenu swaraj!
Have to give us a bit more information to try and help you.
Let's start off with...
Is this a milk pudding?
They are often quite soft at the finish of cooking and then thicken up as they cool.
By dry, do you mean a thick skin has formed on top?
If so this will happen if you don't cover to prevent this skin. Use some plastic wrap or wax paper to cover.