It's intuitively obvious from his question that the keyboard is sending MIDI data to the computer, so clearly he meant that it isn't a MIDI keyboard controller. Many electronic keyboards don't have dedicated octave buttons the way MIDI keyboard controllers typically do.
oriyellow, you have two approaches for resolving this. Most keyboards have some kind of function menu that lets you change various parameters, and usually one of the parameters is an octave setting for the voice/tone you're using. That setting will let you shift the MIDI Note values which are coming from the keyboard up or down by 1 or sometimes 2 octaves. There is usually also a transpose setting that will let you shift up or down by a certain number of semitones, often up to 12 semitones (1 octave), letting you shift up or down by an extra octave if needed. If the keyboard lets you layer voices/tones together, as well as split the keyboard between left and right voices/tones, then there will usually be octave settings for each voice/tone, letting you apply different octave shifts on different MIDI channels.
The second approach is to leave the settings on the keyboard alone and make the changes in Cubase. This is done by adding "MIDI effects" to the track. With MIDI effects you can shift the Note values as desired, although the value to shift by is specified in semitones rather than whole octaves-- so shift by something like +12, +24, or -12, -24, etc., depending on how many octaves you need to shift up or down.