Old Mac not working (Pudsey LS28)

This is a large old Mac that I accidently erased the start up disk for when trying to do a factory reset . It wasn't perfect before that as it was too old for some websites and it used to short my electrics so I had to use a circuit breaker with it . I used it mainly for watching YouTube .
The keyboard is apple and I don't know if it works . It is wired and there is a key missing but it is taped on .
I would like this to go today , Saturday afternoon or Sunday at latest .