How can I get my screen back to full?

I have a lap top and recently got a modem with a new cable company, when the modem got hooked up my laptop cut off and when it came back on my screen was a small square with thick black around the edges, I already tried changing screen resolution and its already in full can you tell me if its my laptop or the new modem?How can I get my screen back to full?
i think you should contact the manufacturer coHow can I get my screen back to full?
it wouldnt be the modem, it should have nothing to with your screen's size. it is something that you need to change on your notebook, im not exactly sure how, i dont have one.

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