Couple of points:
1) Not everyone naturally has a wide vocal range. It depends on your background (e.g. how has your speaking technique been since you were a child) and biology.
2) You unfortunately cannot affect the biology part: your body is biologically what it is and that restricts how easy it is for you to do things. Of course you can train your body and your muscles, go to the gym etc., but it is still your body and its restrictions, not someone else's. Some people simply might have a (biological!) body construction that does not allow a wide vocal range, even though you practice singing for 20 years (I have met male singers that are of the same voice type as me and they struggle with high notes, whereas I can easily sing half an octave higher than them, and that is a lot)! So, some people might have a favorable body construction and they develop a wide range and a good technique in just a few years and just a little advice. That means they have a biologically favourable construction, are more able to control their muscles (note that singing is about muscles and muscle control), and most importantly, that does not mean that you are less hard-working than them: you are just different.
3) Be patient. It usually takes at least three years to automate the control of one muscle group. After that, you must automate another muscle group, and that is how you make progress with your singing. Same goes with vocal range: you need correct instruction and a good voice teacher to train the muscles for healthy singing. Gradually you will develop a wider range but it will most likely not happen in a year. It is like learning to dance: if you have danced and watched good dancers dance or maybe danced with your parents who are awesome dancers since you were a child, you will have a better basis for dancing. Or if you are like me, who has a stiff back and shoulders and never danced until I was 24 years old, it would take 2-3 years to learn the basics of posture and body muscle control. That is what I went through when learning to dance. My singing has gradually gotten better and my vocal range developed for at least five years when I started singing lessons and I'm still learning (of course) new things about singing.