The situation in which a guy suddenly stops paying attention to the girl, does not answer calls, and avoids meeting is different from when a stranger simply does not notice you. In both cases, a special approach is required.
If the subject of your interest does not notice you, being with you in the same company, then there may be two options - he either really ignores you, and does it deliberately, or does not want to show his emotions. Perhaps he is too concerned about his image and considers you unworthy to match him - it is not difficult to recognize a narcissistic proud man. He values his status above all else, always strives to emphasize his individuality and openly despises people whom he does not understand. Such a "copy" should be left alone with himself and not interfere with him enjoying the contemplation of his own "merits".
Guys who are overly shy can cover up, ignoring your obvious interest simply because of indecision, but you will always notice some subtle signs of attention in your direction. If you are not a discerning person, then use reconnaissance in force - make inquiries through girlfriends and friends. And then just take the first step - unobtrusively, playfully, playing, so as not to scare off the fan with your emotionality.
Ignoring due to resentment is more difficult to overcome. First, you need to understand the reason for the alienation, identify the culprits and try to rectify the situation. If the offense is fair, then you should find ways to ask for forgiveness - this is difficult, since he will diligently avoid communication. Use non-verbal communication tools to get started - emails, messages on social networks. There is a risk that he will send them to the trash without even reading them, but often natural curiosity outweighs, and your voice will be heard.
If a guy decided to part with you in this way, "in English", you may not immediately guess about it - the person simply did not have the courage to tell you everything in your eyes. It is not difficult to recognize the finality of his intentions - he may get tired of your importunity and clarify the situation, or he may just stand his ground. Believe me, if there were no serious mistakes on your part, then this is just parting. In any case, an analysis of the situation will not hurt - get rid of self-doubt and think about whether it is worth wasting time and tormenting your heart for the sake of "not your" person.
