This is coming from a girl a year down the road, who is still going through the healing process. So trust me when I say, I know it's hard.
Maybe he broke it off with you or you broke it off with him. For whatever reason, the relationship ended. You may start thinking of all the good times you had together. Wanting to call him or text him because you miss him. Well, as someone who did all of that and stretched out a relationship a few more months that still ended... I'm here to tell you, don't do it.
While yes, there were good times, don't forget the bad. All the fights and tears that kept you up for hours on end. Remember why the relationship ended and how you felt majority of the time you were together. They say time heals all wounds. I wish I could give you a timeframe of when the hurt stops, but to be honest, my relationship lasted about 3 years and after a year of being broke up, I still randomly miss him... Especially when memories on social bring their picture up out of nowhere. But the tears that used to hit you daily, will turn monthly and eventually you'll let go.
Always remember that you can still love someone, but need to let go of them.
Surround yourself with family or friends. Take a girls night out. Have a wine night. Just go visit them to talk or visit them to keep yourself from missing him. While you know it's out of love, be sure if you're not ready to hear them tell you to move on or anything else that isn't helpful, it's also okay to distance yourself and give yourself more time to heal.
My best piece of advice is to spend sometime with yourself. Allow the healing process to take place. Give yourself the time to cry, be sad and mourn, because this is a loss. While it's important to let go if the relationship wasn't right, you need to know it's okay to be sad.
But most importantly spend time with God. I can tell you my healing came more from praying and crying out to God, than anything else. This step is where you'll find that happiness can be created within and doesn't need to come from someone else.
You're probably scared of going on first dates again, having to learn new things about a person and going through that awkwardness of trying to get comfortable all over again. Some dates are going to be horrible, but then there will be a few dates that go amazing. You might talk to a guy you really like, who doesn't like you back. You'll talk to guys who really like you, but you don't feel the same. Just remember everything happens in God's timing - His plan is far better than yours.
But it'll all be worth it once you find that person who makes you happy, makes you laugh... and when you can say his name and it fits into 1 Corinthians 13:4-8 "Love is patient, love is kind. It does not envy, it does not boast, it is not proud. It does not dishonor others, it is not self-seeking, it is not easily angered, it keeps no record of wrongs. Love does not delight in evil but rejoices with the truth. It always protects, always trusts, always hopes, always perseveres."
Friend, it's going to be hard, but as long as you trust in God, you'll be okay. I promise.