There could be several reasons why an old friend might stop talking to you and then start again without any explanation. Some possible explanations include:
Personal issues: Your friend might have been going through personal problems or challenging times that made them withdraw from social interactions, including their friendship with you. Once they resolved or dealt with those issues, they might have felt ready to reconnect.
Misunderstanding or conflict: There might have been a misunderstanding or disagreement between the two of you that led to a temporary rift in your friendship. After some time, they might have realized the importance of your friendship and decided to reach out again.
Change in priorities: Life circumstances can change people's priorities, such as starting a new job, moving to a different city, or getting into a new relationship. These changes might have caused your friend to become distant temporarily, but they might have felt more settled later and reached out again.
Feeling overwhelmed or introverted: Some people, when facing stress or feeling overwhelmed, might withdraw from social interactions, even with close friends. They might have needed time to recharge and regain their emotional balance before reconnecting.
Fear of judgment: Your friend might have felt ashamed or embarrassed about something that happened in their life and withdrew to avoid judgment or criticism. As time passed, they might have become more comfortable with themselves and decided to reconnect.
Lack of communication skills: It's possible that your friend struggles with communication or expressing their feelings. They might have found it challenging to explain their reasons for distancing themselves initially, but eventually felt ready to rebuild the friendship.
Regret or remorse: They might have regretted their decision to cut off contact and realized that they missed the friendship. In such cases, they might have mustered the courage to reach out and apologize for their actions.
It's important to remember that everyone goes through ups and downs in life, and sometimes friendships can experience rough patches. If your friend has resumed communication, you could choose to accept their attempt to reconnect and take the opportunity to talk openly about what happened, or you can decide if the friendship is worth rebuilding. Keep in mind that it's essential to communicate honestly and openly with each other to understand each other's perspectives and feelings.