Only systems and workstations can be reinstalled. There is no good way to redo the system. Let's reinstall the system.

2.

I have never encountered such a situation. Is the computer connected to the internet (including external network and local area network), and is a USB flash drive plugged in? If yes, kill the virus, or try to delete the antivirus software (sometimes the antivirus software accidentally kills or disables some functions of the software). If it doesn't work, plug and unplug the connecting cable again. If it doesn't work, it can only be reinstalled according to the engineer's method. It is recommended not to connect to the internet, especially the external network, and try not to plug in the USB flash drive. Reinstall the system and restart the workstation according to the engineer's requirements. Check whether the connecting cable is loose. If it doesn't work, it can only be reinstalled. Suggest repairing it.