Be strong and single-minded in your approach. Now you know what you want, it will be easier to ignore everyone Else's advice and well meaning contributions. If this person is your lost love, then trust your own judgment. You know them better than anyone else so you should be able to work out how best to get them to return to you.
Be sure of your motives in particular that you are not trying to rekindle lost love because you are afraid of being on your own. Being single can be fun, it just takes a little getting used to. It is hard to be objective when emotions are involved so it is always a good idea to write down a list of all the reasons why you want this person back. Also write down a list of why the relationship failed. Obviously you would expect the first list to be the long one!
Sometimes people break up and it is the wrong decision. We can all take our lives for granted and as we get older we sometimes wonder if we have missed out. These feelings can cause people to do silly things like walking out on their relationship. If being apart has shown you the error of your ways, then make contact with them and ask to meet up.
If you hurt your ex, you must be prepared to take things very slowly and at their pace. They are unlikely to fall in your arms declaring undying love if you have hurt them badly. If they do, you must still proceed with caution as any lingering problems need to be resolved.
Be aware that no matter how much you miss the other person, there was a reason why you broke up and that needs to be dealt with to prevent it causing fresh problems. There are some things that just cannot be overcome no matter how much we love the other person. The idea that love conquers everything belongs in Hollywood not in real life.
If, for example, you broke up because your partner wants children and you don't then it is unfair to get back together unless you have changed your mind. Denying another person the chance of having children causes the type of pressure that very few if any relationships can survive. The resentment will probably kill the love you shared.
If you have issues that can be resolved with some mutual work, then go for it. Life is too short to waste time in regrets. Sometimes it is not always the easy way forward to try to win back lost love but often it is the best step you could ever take.