I have changed my home folder name through command
mv olderFolder newFolder and then restarted, but not able to login. What step did I miss?
After rename your home directory you should still tell linux about your new home directory This can be done by editing /etc/passwd file
Just open that file and change /home/olderFolder to /home/newFolder
It is not a good idea (as you found out) to rename your home folder.
If you can, log in as root and rename your folder by issuing
If you don't have a root login, get an Live CD, boot it, don't install but simply 'repair' an existing installation. Mount the drive and rename the home folder similar to what is shown above.