I often have problems with this. If it's problems with forgetting things to do or important dates there are some things you can do. For important dates putting them on a calender or phone can help. My phone will actually remind me a day ahead or hour ahead of time so i can be prepared. IF it's things in the course of a day then i would suggest making lists. I love lists! lol They are good for people who can't remember more than a couple things at a time. And you get a sense of accomplishment when you start checking things off!
Hope this helps. And don't be too hard on yourself. Only elephants remember everything