reset network manager to its defaults

[shimjitht009]

I don't know how but i had messed up with some installations (was trying to install wvdial) and due to this my Data-card doesn't detects under mobile broadband but it can be seen while executing 'lsusb'.Earlier it was automatically detected and i was able to connect by making a mobile broadband connection.Now the situation is that i was not able to use my Datacard through creating a new mobile broadband connection nor through wvdial. Is there a way to reset the network manager to its defaults without complete re-installation of the OS? Is there a solution using live CD? I am using Ubuntu 14.04 lts.

[shimjitht009]

when trying to connect the datacard, it is showing modem.sh missing or no such file or directory.Iam using ubuntu 14.04LTS. what to do?