Do you know where your old workspace folder is located? Were the files physically located/nested in the workspace folder?

You could open Eclipse with a new different (empty) workspace folder or File -> Switch Workspace. Then use File-> Import -> General -> Existing Projects into Workspace. Use "Select root directory" and use Browse... to locate the folder that contains your projects, assuming they are still on disk somewhere. Note the "Copy projects into workspace" checkbox. If this is checked the project folders will be copied to be physically nested in the workspace folder. If not checked, the projects will remain at their current disk location.