Can young men get erectile dysfunction?

Yes. Remember, 50% of causes of erectile dysfunction are emotional - anxiety, depression, ptsd - and as such can be experienced in younger people without any medical conditions. As well, younger men may have testosterone deficiency which can affect both desire and performance.
Yes. While there are many reasons why men get erectile dysfunction, when i see men in their late teens and 20s have erectile dysfunction, there is often a psychological component to it. Drugs such as anti-depressants, use of illicit drugs such as pot, alcohol abuse, as well as chronic diseases such as diabetes and high blood pressure can all contribute to erectile dysfunction at this age.