Stanislav, if everything is lost then the only solution is to recreate your site by copy and paste from the online site content to a new project, it cannot be restored from ftp.

In the failed PC if you can still read the hard disk perhaps by removing and connecting to another PC (ie it hasn't collapsed and has not been formatted over), then you could copy the whole project to a new PC, and of course if you have ever exported the project to create an iwzip file and have access to it, recovery will be very simple.

If your drive is still there you can try this also:

https://helpcenter.websitex5.com/de/post/177728

or

https://helpcenter.websitex5.com/de/post/47713