Whenever I am trying to lock or unlock any file in the project it gives me error :
svn : Can not Parse lock / entries hashfile
Now I am not able to take lock on file.
Some clues : 1. We have just migrated our svn repositories from one url to other url
Is there any way I can reset the lock file of repository.
It is possible your repository was damaged in the migration (though check the working copy first, as Bert suggests — never mess with your repo's innards unless you have no other choice). If so, you can "manually expire" all locks on the repository by deleting the <root>/db/locks folder.
This will not affect your repo's contents, but will destroy all lock data. Also be aware that, if your repo's lock data got corrupted, it's entirely possible that other data did as well. Keep the pre-migration backups around.