Hi Shankar ,
This has happened to me lot of time.
I would recommend you to use , FindChild methid to find these objects and then insert tex into it and click OK button.
Also , as Tanya has mentioned , give a try to find the object using "Object Spy". [If the object is able to map , it will highlight with red rectangle].
Once you map it , you can see the advanced properties , fields and methods of the mapped object. You can use the suitable method to insert text into it.
Hint:
If both of the method does not work. Record a script. It may show you some co-ordinates and you can use combination click and keypress to insert a value to these textboxes.
