Assuming You want to do a Factory Restore/Recovery
You can try tapping f9 to get into the factory restore menu.
I gather that sometimes ASUS has a thing called boot booster which may get in the way. If f9 doesn't work after a few goes tap F2, I think, to get into the BIOS. Turn Boot Booster off then try F9.
Factory restore/recovery will delete all your data and put your PC in the condition it was when you first turned it on.
If You want to run a System Repair
Given you can't make one. A reliable iso source has been given above.
The F11 (or F8?) key may require turning off Boot Booster as described above.