http://kb.mozillazine.org/Disappearing_mail

None of these help or work. Please understand ones I am trying to open Inbox, it just continually trying to open (neverending) it and nothing happen, just all looks like somehow stacked. Can not search messages in Inbox, but can in all subfolders of Inbox.

I'm not sure I really understand your problem.

Try to start Windows in safe mode with networking enabled. - Win10 https://support.microsoft.com/en-us/help/12376/windows-10-start-your-pc-in-safe-mode - Win8 https://support.microsoft.com/en-us/help/17076/windows-8-startup-settings-safe-mode - Win7 https://support.microsoft.com/en-us/help/17419/windows-7-advanced-startup-options-safe-mode#start-computer-safe-mode=windows-7

Still in Windows safe mode, start Thunderbird in safe mode. - https://support.mozilla.org/kb/safe-mode

Does that make any difference?

I will try it, but I think already tried and no change. Still the same. Let me try to explain again. My Inbox is generally quite big about 3,8G, but it consists of about 25 subfolders. Ones I open Thunderbird all looks almost fine (bit too slow) and works fine. Write message, send message, search messages (except the Inbox) unless I try to open Inbox it just stops and shows a continuing neverending process, like trying to open Inbox. It is the same if i try to search inside Inbox just searching. I can not see any message in Inbox folder (but all messages in the inbox subfolders are OK visible. I have tried to delete Inbox.msf, but the only change was not opening, but 0 messages in Inbox. So got back the same msf file and all is as it was before deleting. If I am looking into Application data, mail, inbox, it still shows all data. I have done already several times like year or two years ago and so reindexing my folders in Inbox becasue of the notice: Inbox is full. Ones all finished as per advices from support all warks fine for longer period. I have also created subfolders of archiv for period of years, to minimize size of the subfolders, which helps to extend periods for such crashes.

My Inbox is generally quite big about 3,8G, but it consists of about 25 subfolders.

What's important is the size of Inbox itself, subfolders underneath Inbox doesn't really matter. I'd assume that you somehow accumulate messages in Inbox, and that your Inbox file is still a significant size, even though it's probably less than 3.8 GB.

I have done already several times like year or two years ago and so reindexing my folders in Inbox becasue of the notice: Inbox is full.

This is typically a sign of mail file corruption. If the corruption isn't severe it can usually be fixed by rebuilding the index file.

Note, corruption is often caused by anti-virus software messing with Thunderbird mail files. It is therefore recommended to create an exception for the Thunderbird profile folder, so that the real-time scanner won't attempt to scan the profile with your mail.

For more information on the profile location see http://kb.mozillazine.org/Profile_folder_-_Thunderbird

Also see http://kb.mozillazine.org/Keep_it_working_-_Thunderbird

Starting Windows in safe mode disables anti-virus software, which may have an effect when using Thunderbird, e.g. anti-virus software not blocking access to mail files.

I have also created subfolders of archiv for period of years, to minimize size of the subfolders

That's a good idea, however, most important is to minimize the size of the Inbox.

Nothing helped and what even happened now I did not see anything in my inbox, just it was empty. So all is lost, because it has deleted msf file and now inbox shows 0. Anyway I tried to load my last backup, dated March 18, but find out that Inbox file was missing, simply did not backed up??? So must use one from October 2016. My question is how to maintain Inbox as small as possible where to move messages. I have moved several years into Archive. Would it help? Is there any other way how to shrink inbox or even sent folders, unless to delete messages?

Personally I move messages I'm done with to a folder 'Read'. Also archiving is a good idea, and it has exactly the same effect: to keep Inbox clean and tidy. Basically the same goes for the Sent folder, I create yearly archives underneath 'Sent'. If you don't want to mix up received and sent messages, make sure not to use the Archive function for sent messages. Move them manually instead.

As important, let Thunderbird automatically compact folders. More information in this article. http://kb.mozillazine.org/Compacting_folders

Third, follow these general instructions wrt your anti-virus software: Create an exception in your anti-virus software for the Thunderbird profile folder, so that the anti-virus real-time scanner will not scan it. http://kb.mozillazine.org/Profile_folder_-_Thunderbird

Don't let your anti-virus software scan incoming and outgoing messages.

Don't let your anti-virus software scan attachments.

Don't let your anti-virus software intercept your secure connection to the server.

Remove any add-ons your anti-virus software may have installed in Thunderbird.

Keep it working. http://kb.mozillazine.org/Keep_it_working_-_Thunderbird

Fourth, create full backups of your Thunderbird profile on a regular basis. It's as simple as copying a folder. https://support.mozilla.org/kb/profiles-where-thunderbird-stores-user-data#w_backing-up-a-profile