problem 1

when ever i use update command it shows
N: Ignoring file 'some-ppa.list.save.3' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
N: Ignoring file 'some-ppa.list.save.1' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
N: Ignoring file 'some-ppa.list.save.4' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
N: Ignoring file 'some-ppa.list.save.2' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
N: Ignoring file 'some-ppa.list.save.5' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension

problem 2
later there was login loop problem so i created another user .This user running in test .
mynewuser is not in the sudoers file. This incident will be reported.

problem 3
how can i take back my old files and folder .Now the old user login iam not seeing the user.

to 1. As the reported files are ignored, there's no problem. You may delete them.

to 2. Please describe the login loop problem in more detail. Can you still change to your first user home directory with su - prajit? Replace prajit with the username of your first user.

to 3. The answer depends on the answer to problem 2.

Moved: This thread is more suitable in <Ubuntu> and has been moved accordingly to help your thread/question get the exposure it deserves.

to 2: you need to add newuser to sudoers if you want to use sudo with that user. But you cannot do that with this user, you need to use another user (root or the olduser) which has already right to modify sudoers.
to 3: without knowing what's happened hard to say anything.