Have you actually saved any projects to you local PC yet?

If you have not then opening projects in offline mode will not do anything. You also cannot open any online projects or access any that may already be listed in the left hand panel.

Yes all Projects were allways saved on my PC. As I Wrote everthing was normaly and then without any notice of the programm I could  not open the projects anymore. The problem seem to be with the double click in the project file (schematic / PBC) . It doesen't responsd to my clicks. If I Start a new Projekt and save it i can open the projekt file but not open the Schematic or PBC. I also can't open the file with the open button. Do you have any Idea ? Thanks a lot for your answer 

Save a copy of your local Easyeda data storage directory and then try uninstall/reinstall the Desktop Client to see if that changes anything. When you do:  do you get this message:  ?

Hello again, I never got this message. I deleted in the past the Programm several times without succcess. There was no changes. As you wrote I tryed it again, but now I deleted also all under file (project and so on) after the removal of EasyEDA on PC. There after I installed again the programm and I created  a Test file to the empty project file. With this test file the Programm was working normal. Then I copied the backup file with all own projects, again to the project file. Unfortunately the same problem came back (no function on double clicks). I deleted all own files again except the test file (schematic/PBC). Problem was solved again. Then I copied step by step all own files from my backup to the project file. Out of 25 files I found 2 files wich the nown problem occurs again. I have no idea why these 2 files are causing the problem ? The programm works now normal without this 2 files. I guess that I edited this 2 files as last package before I restarted the programm with the described failure. Just for INFO how the problems began: After saving the file I switched off the PC and after a normal start at the next day I got the Problem without any indication. I would like to THANK YOU for your help !!!

Ah! Sorry! I thought there was something else that I had forgotten about this behaviour. If you look in the EasyEDA data storage directory, you may find some extra "info"  files in there. They cause this not opening with no warning behaviour. There is a post about it in the last few days, but basically if you delete them, then the problem goes away!

This is the post about the "info" files: [https://easyeda.com/forum/topic/Unable-to-open-either-PCB-or-Schematic-from-project-pane-ef3014a662dc4282a271d82241d4aeb7](https://easyeda.com/forum/topic/Unable-to-open-either-PCB-or-Schematic-from-project-pane-ef3014a662dc4282a271d82241d4aeb7)

I was reading this post before I made the new topic. But this post was not helpfully for my problems. Even with the folder boo, I coul'd  solve the problem. Thanks for your support