I am running Windows 7, Arduino 1.6.5, and NodeMCU V1.0. I have tried three of the latter with the same result.
So the problem doesn't seem to be in the NodeMCU.
So I suspected the Windows USB driver. Windows Device Manager shows the NodeMCU's CP2102 USB-to-UART bridge under Unspecified and operating on COM10 where I had been for a long time. I checked for a CP2102 update and the Silicon Labs software said I didn't need one. I don't know if I should do a re-install.
The only other thing I can think to do now is re-install Arduino 1.6.5 which I hate to do because I had tried to update to a newer stable version a good while ago and had nothing but trouble. Arduino 1.6.5 works fine for me so far. I just wonder if it has become corrupted. If it is not broke i sure hate to "fix" it.
Any thoughts?