Kmail is not showing any messages in 'unified mailboxes' or 'Local Folders'.

I can see mail files intact in '/home/me/.local/share/local-mail' folder. I can also see my identity and receiving and sending accounts intact and unchanged, except, in receiving accounts other than 'local folder' and 'maildir_resource_x' folder I can see 'offline' tag appearing.

I was trying to migrate kmail on another laptop. I was not able to receive,but was able to send messages. On the laptop where this problem happened now,kmail was correctly working. I decided to compare settings across the laptops. So, I went to 'settings > receiving accounts' where I received mails from four mail accounts and all of which were working.

Among the receiving accounts were listings for 'akonadi_maildir_resource_2' and 'Local folders'. These two were not what I created, but kmail put them there at some point of time.

Now I selected each of them one after the other, clicked on 'modify' , and was reading the entries in the dialog that came up. I did not intend to change and I did not change. I was reading the entries. The dialog was open and in dolphin, I was navigating in the folders under '/home/me/.local/share/local-mail'. I saw a starnge message popping up and saying(to the effect), 'the folder you just deleted contained messages......' Suddenly I saw 'unified mailboxes' and 'local folder' content disppearing and coming back and then the content disappeared for good.
Now, once in a while, I see a notification flashing, ' Error while trying to get the local inbox folder, aborting mail check.Timeout trying to get lock. '

I have earlier experience of kmail not showing any message listing and then I closed kmail, in the terminal manually stopped akonadi server and restarted kmail. Messages all reappeared. Several times it has happened.Messages have re-appeared too. I have browsed through settings many times before, tinkered with them and got them to work. This never happened.

I tried the same steps in this case and re-booted the system, but messages do not list. As I said before, I can see message files in local-mail folders.

I can see in the status bar 'unknown' . I did not use to get it earlier.[update, kmail does not show this anymore and has started to show some newly arrived messages which are getting saved in '/home/me/.local/share/.local-mail.directory/inbox/cur' ]