I cannot install the system

So...I need help.I have a MacAir that I want to franckly set to factory settings, because I'm at my wit's end and I really

don't care if something is lost. So I entered to command + r like any tutorial said, erased my disk - I didn't touch anything

that I didn't need to - and then put the option to reinstall the system, which for some reason is OS X The Captain - and I can guarantee

you that the MacAir had the macOS 10.14 Mojave but can support the last update is just I forgot to install it - but I figured I could install an outdated version

and then update the system, and naturally

it appeared that I could not since the date for some reason does not let me and you might say well you only need to go to Terminal and change

it, right? ; you even can do that you might be saying.

I cannot.

You see, the reason why I'm setting everything to factory settings it's because the keyboard is crazy and it couldn't be set up normally in Preference System. For some reason when I enter to command + s it writes ... normal. The a is the a, the b is the b and the letters appear as letters...but once you enter the "normal screen" the keyboard goes wild and instead of letters are symbols I don't understand which makes it impossible to write the password of ANY account on the laptop...even when you create another account to change it from the very same laptop. And even if I could for some reason I.CAN'T.WRITE.ON.THE.TERMINAL.

So, I want help in how to reinstall it when this situation happens; if this doesn't solve the problem with the keyboard then I'll just take it to a professional because this is simply just too much for me . I just

want to install the system.

Please, help me. I'm desperate.