I have no idea what happened, but suddenly my Windows 10 VM that was fully functioning 24 hours ago will not open and I get a black screen that says there's no Windows operating system in the VM. I had a backup clone that got accidentally trashed and now I only have a clone that is a year old - which I am able to open and updated the Windows on that but my problem is that all my newly licensed Quickbooks Enterprise is in the VM that I can't open and I can't reinstall it and use it in this replacement because the license demands that it be uninstalled first from the previous machine (which I can't open!)... I keep seeing people here say to download another version of Windows 10 and try to reinstall it but I don't know how you do that on a VM that won't function (and wouldn't I lose the QB application anyway?) I am presuming that a new QB Enterprise would think that this new VM is a different computer and that the license would be attached to the old one - yes? I have no idea what they "see" as a device. Any help would be appreciated. I'm on an iMac running Ventura 13.7.5 and running Parallels 18.3.2 (I haven't upgraded because you took away "Print to PDF Mac" and I desperately need that).
I would backup this non-working VM to an external disk, thus, you won't loose anything when you now try to reinstall Windows 10 as was suggested here. At least I would give that a try to see if it resolves your issue with the VM. Regarding your QB license (I use QB Prem myself) I would contact either my QB dealer or Intuit support and ask them for help with your license (you might need proof of purchase). If your old VM was saved on the same Mac it should have the same ID as your current VM, thus, it should not be considered a different machine.
One more thing, after you got your black screen create a lock (Help -> Send Technical Data), send it to Parallels support and post your ticket number here. Support hopefully checks your log and might have another suggestion how to fix your VM.