Wow, you already got so much of terrible advice. I guess people are telling you what would work for them and not necessarily for you. So let me provide you with some bad advice. 

Accept reality. Relationships do sometimes end. It is sad, but it is true. 

Don't beg unless there is something to forgive. If you just grown apart there is nothing to do about it. Treat her with love, let her know how you feel and close this chapter. Refrain from calling her names, blaming her and similar stuff. Apologies if you already did. Remember that ideally you want to stay friends.

Year is already long time, but still allow yourself to grief. There is nothing bad on feeling sad, melanchic or depressed. Don't hide from it, process your feelings. 

Once you start feeling better, put yourself out there and start looking for for someone new.