sound like you already tried this:
automatically starting the time service and reregistering the service? like from here:
Time Synchronization Failed - Microsoft Community
basic sequence of commands:
start cmd.exe as admin
net stop w32time
w32tm /unregister
w32tm /register
net start w32time
w32tm /resync
then check the system time.
net stop w32time
w32tm /tz
run w32tm.exe /?
to see options. there is a debug option to log info to a file
but I have never tried using it to see how helpful it is.
(just looked at the debug option, not very useful, showed ip address and socket number of the time server)
w32tm /query /source
showed the name of the time server being used
in my case
time.windows.com
you should also boot into bios and check that the system time and date are correct. then shutdown, disconnect the power, then repower back up and go into bios and check the data and time again and confirm they are still correct.
(motherboard cmos button battery should last 4 or 5 years then has to be replaced) I think these are 2032 batteries
windows time server should still work though but they get attacked by hackers to screw up systems.
you can download the windows image directly from microsoft without needing to buy a new key. use the link provide by the last post:
Download Windows 10 (microsoft.com)
you can enter in your old key or skip it and log in with your microsoft account and your system should get validated from your past use of the key. (same hardware)