Question Something got messed up with my Windows and the network is not working

[photon123]

I was browsing the internet, and suddenly the screen flickered a few times and went back to normal. This didn't look right to me and I rebooted the system. Windows didn't boot properly for a few times, but after a few attempts went back to booting normally. Strangely though there is no internet access. Windows network settings app doesn't open. Windows Diagnostics says that Diagnostics Policy Service is not running. If I try to start it, it says: Error 5: Access is denied.
I tried Windows Recovery, but unfortunately there are no restore points. It seems like it was set to store data on a drive that was full, and didn't store any. I didn't download anything recently and Windows update history shows nothing recent. Just prior to this happening I did look up information on the Ukraine conflict to figure out what was going on, and I do wonder if some site somehow manged to infect my system through some exploit. Avast anti-virus and RogueKiller don't find anything unusual. I also didn't notice anything unusual other than the network not working. I also have Ubuntu installed on the same drive, and it works fine with normal internet access.
Any ideas what happened and how can I fix it?

 

[rgd1101]

full system spec? include brand and model of the psu
how full is your ssd?

 

[Lutfij]

You might want to try using malwarebytes to be double sure that your system hasn't been infected. As a side note, please list the specs to your build like so;
CPU:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS:

Since you've posted this thread in the Windows 10 section, please include he version(not edition) of the OS.

 

[photon123]

Windows 10 Pro 21H2
OS build 19044.1526
Windows Feature Experience Pack 120.2212.4170.0

I don't think this is hardware related. The system seems stable. I have this system for years and it works fine. I did replace the PSU two months ago because the old one got noisy, but is was working fine since. Something happened now with Windows.
Intel 6700K
32 GB DRAM
It was just the drive with Windows installation, that got full. I have plenty of space on other drives and after this happened moved some staff to other drives to free up space.

 

[photon123]

Any ideas? I have been using Ubuntu, which is also installed on the same system and it works fine. I didn't find a way to fix Windows. Any ideas? Or should I reinstall it?
Windows works fine, except that there is no network connection.