Even after a clean re-install of Windows this problem has returned: first I could not install apps from the Store, then the Store itself would not open.
Without success I have tried
running the Store Trouble Shooter --- it reports such things as Store configuration may be damaged, cache may be corrupted but it cannot repair them
running SFC/SCANNOW which did not find any errors in the Registry
There is another CMD scan & fix which may restore the system to health if it finds a problem ---- I cannot remember it now (I thought the problem was finished with!)
What do I do now?