Windows 10 is buggy. How (is it possible) to roll back to the "eight"?

Question

Windows

Recently installed (upgraded) Windows 8.1 Pro to Windows 10 Pro. The system was put "crooked" application "Settings" does not open (=> it is impossible to use "return to factory settings"), it is impossible to put the laptop (HP Pavilion g6-sr2317) into sleep mode!. Need help in restoring from "ten" to "eight".
IMPORTANT!: The system is most likely not from the manufacturer, because a month ago a hard drive flew, a new one was installed in the service, they assured that it was licensed. But I do not exclude the possibility of recovery from a hidden partition. Help, maybe it's possible to restore a Windows 8/8.1 distribution?

Answer 1

As far as I know, only a clean install can help. Perhaps even Win10 will work adequately with this installation.

Answer 2

As far as I understand, you suggest me to save all the necessary data to an external drive and cleanly reinstall Win10? For me, it's better if there is a distribution kit for "my" Windows 8.1, it's kind of more familiar.