Lost my project and unable to create any new one

Dear all,

I was working on a workflow yesterday and regularly saved my work.

As my PC was slow, I decided to close all apps and restart it.

when I launched again Knime, my workflow disappeared. On the right part of the main Knime window, my workflow was not listed. I run a search on all my machine and could not find it. I even restored the bin. But this workflow totally disappeared.

I switched off my PC.

This morning I decided to create a new workflow and re-do my all job.

But Knime refuses to create a new workflow. No error message.

I also tried to open an existing workflow and again, no response.

I am using version 5.4.3.

Could anyone tell me what could cause this behaviour?

many thanks

Esmé