I am developing an app where I have to lock some android default Apps such as messaging, email, gtalk, etc . How to do it, i have no idea. Please help me with some relevant code or link.
Also, want to know how can i get the list of all application installed in android phone.
AFAIK You will have to write a launcher that will remember whether the application needs to be launched or not. There is a sample launcher that comes with SDK.You can start from there. But this is not a foolproof solution. If user installs different Launcher then this wont work.
To get the list of all applications installed you can use PackageManager.getInstalledApplications