How to reinstall windows 7 system from hidden partition with ubuntu dual boot?

Question

Windows

Asus laptop with a hidden partition of licensed windows 7 (preinstalled). Parallel to it, Ubuntu was installed on a separate logical disk. When turned on, the OS selection menu appears. Previously, the recovery was called by pressing F9 when turned on, now it does not work, most likely because of the dual block. Neither escape nor F1-12, del. How to reinstall win?
There is an idea to install a pirate over the old system in order to overwrite grub2 (efi, or whatever, I don’t remember) and then, in theory, it should normally recover through f9, but not a fact.

Answer 1

Solution found. In Dualbut, select the download of windows 7, and immediately after that, poke F9.