Message appeared which said "error occurred while loading the project 
Автор: Joanna M.Good morning,
I try to get into "project selection" and continue my project but instead of opening, a message appeared which said "error occurred while loading the project (object reference not set to an instance of an object)". Every time I click on it that message appears.
Then I used helpcenter, and i found this:
Error while Project Loading
Autor: IncomediaVisited 5604, Followers 19, Udostępniony 0
If you receive this message, go to step 0 and select "Preference". The option "Project folder" shows you the path in which your WebSite X5 Evolution 9 project has been saved.
Go in this folder and proceed as follows:
1. Delete the "preview" and "upload" folder.
2. Delete also the files project.iwprj and metadata.xml.
3. Rename the file backup.iwprj into project.iwprj.
4. Open the program and select it from your recent projects.
I followed the steps, and In the 3 point I was supposed to renamed backup.iwprj into project.iwprj., but in my case I have only "backup" without "iwprj". but i renamed it. After opening program my project has gone. Does it meant that I will not recover it anymore?
Thank you,
Joanna.
I hope that you did not over wrote the original project.iwprj, because then it's gone.
I also hope you have made a copy of all files / the complete folder before renaming thibgs and deleting things.
Did you made previously a backup in step5 export project from time to time, then you can use one of those.
If all is no then I am afraid you need to start over again.
Make backup's of your project regurly! (step5 export project) Also if you start over.
If you start messing with files make also a backup of the complete folder so there is always a point to go back to.
But reading your post it's i have a feeling it's too late advice....sorry.