Earlier i used to see,modify layouts in my ADT itself on Graphical layout Editor tab,but now iam not able see now is there any thing to update or that feature is removed or any reason.if these is any way to get it back please let me know
There are some workaround you can try :
1. Change android version in your layout editor
Try to increase or decrease android version in your layout editor. Sometimes this trick solve the problem.
2. Create new workspace
Create new workspace in eclipse and import your project in new workspace. Sometimes a new workspace solve this kind of issues.