I up graded to the latest version and now it will not load plug ins, crashes randomly I have to restart the computer to get it open again, Now it will not load a file at all, even recent ones I have saved. Can I delete it and go back to the early version which was working.
Yes, you can get installers for earlier versions of Dorico from this webpage. Just scroll down until you can see this section:
But before doing that, please start the current Dorico version again, until the hub window apppears, then please do from the Dorico menu Help > Create Diagnostic Report which will create a zip file on your desktop. That zip file please attach to a reply here. From the contained logs and crash files I hope to be able to tell you what is wrong with your current installation.