I wrote a program including a dashboard. That also went on for a while. Now when I open the dashboard I get the message "Welcome to the Node-RED Dashboard
Please add some UI nodes to your flow and redeploy."
Of course there are UI nodes in my flow because it works.
Open the Developer Tools in the browser, refresh the page and see if any errors are shown.
Which browser are you using and can you try a different browser?
Also stop node red and start it again in a command window. Then copy/paste the log output from the command window. Copy/paste please not screenshot.