Re- establish breast milk...pleaseeee help!!!

Piri
Okay, so I breastfeed for about a week when my daughter was born. I excusively pumped for about a month after that. Then I started giving her formula because my milk wasn't agreeing with her stomach because of my diet and I also wasn't producing enough. She's 4 month now and I want to start back giving her breast milk. I'm not even going to try to get her to latch on because I've always had a hard time with that but I want to go back to excusively pumping but I don't think I have any milk. Can someone give me some advice on how to produce breast milk again? I'm going to start back pumping and stuff to help get my milk back but is there anything I can take to produce it again?