It could be a strike due to bottle preference.
When we had ours, I found that the moment her lips touched a bottle teat she would stop crying and opened up. For the first day I started feeds by touching the bottle to her mouth, then when she opened, latched her on instead. Took numerous attempts, quite often not successfully feeding in that waking session.
Since I wasn't worried about weight and I knew it was strike, then I offered no more bottles. Wrote off three days, lots of time in bed and skin and skin. Be warned it was very stressful and lots of stubborness is required. I knew in the long run, that carrying on BF was the best thing for her. If she cried throughout a whole feed, then would sleep. I was then able to feed her either asleep or when she had literally just woken up and still drowsy. Since I was holding her the entire time, then I could gauge this. She was having dreamfeeds at nights anyway so the feeding whilst sleeping was relatively easy. This meant that I still got feeds into her about once every 4-5hours.
Actually at first, we did give a few feeds by syringe, but soon went to breast or nothing approach.
I have consistently struggled with slow-letdown. I found if she was going through a fussy period, then if I could get to let down, I could get a feed. So lots of hand massaging and sometimes expressing to try and stimulate the let down. Then put LO on quickly. With the bottle induced strike, I think she got used to having the milk instantly.
Depending on your situation, this might not work for you (e.g. weight concerns). If this has been going on for a few days, then you will need to express to keep your supply up.
If you want to try and get her back on the breast, then I would make sure she isn't hungry before you start i.e. get her properly fed up before going for it.
You can try and make the bottles a littler harder for her. Lot of switching from side to side (like you would during a BF). The pauses will slow down things a bit. Having a slower flow teat on. Or (I know it's a lot of work) switch to feeding via another method.
Most of you, don't force the baby on. Offer her the breast, but don't persist, even if your doing it all the time.
What are the weight issues at the moment.
Remember, it's not a mandatory thing to breastfeed, so make sure it's what you want to do and if it doesn't work for you, then so be it. At this point, you expressing a few feeds for her a day will give the same benefit as continuing BF but with formula top ups.
If you can get help in real life, then do. BF cafes, LLL or hiring a consultant.
For other ideas, then google kellymom and nursing strikes. There's a lot of information on there to help determine what the cause could be based on YOUR experiences, inc reflux, fast let down and the other usual suspects.
Good luck