Hi, I'd like to help you with your question.
It is common to think about someone after a break up, especially if the break up was not your idea.
One of the most important things to do after a break up is take time to mourn the loss. Since people break up all the time most people believe it should be no big deal to end a relationship, especially if you were not engaged or married. But once you form that bond with someone, ending that bond is very hard. It is a loss. So taking time to mourn is important or it may be hard to let go.
If you have had time to mourn, then this may be a matter of time and keeping busy. Both will help you not only move on from your old relationship but help you find a new one. Allowing yourself more time is important. It's only been a month or so and that is a short time when you consider that you probably were in the relationship for a longer period of time. If you are still feeling the same after 6 months, then you should consider seeking out therapy to help you. But give yourself at least that long.
Also, be sure you are keeping busy. Go out with friends, especially on weekends, and keep yourself occupied with activities. It may sound like common advice but it works. Also, consider getting more involved with groups, hobbies, classes or other activities. This not only serves to keep you from thinking too much about your break up, but it helps to open you up to new relationships. The more people you meet, the more chance you have of finding someone else to be with.
I hope this has helped,