Hi Emmy,
This sounds so familiar. At exactly the same age my DD, now 3.4 suddenly started refusing all her favourites pretty much - and certainly anything that had been off the rota for a couple of weeks.
Aitch gave me some great advice about neophobia, and actually, if you look at some of the old transcripts from the live web chats, Dr Tanya Byron has some interesting things to say about neophobia - apparently it can relate to foods they have previously liked and enjoyed.
The best advice is to stay calm, not force the issue, give her what she will eat. I always used to say, just eat one pea - that's all, then you can eat what you want. She could usually manage that.
This was of course after one of my most shameful bits of out of control parenting ever where I put every single one of her favourite toys on the shelf in order to make her eat. She didn't - I lost my rag, and nothing was achieved.
Please be assured, it's a phase that might only last a month or two - maybe longer, but they do come out the other side, so it's best to try and ride it out serenely with a smile on your face. And my advice - don't serve anything you have slaved over during this fussy period - it will make you less emotional about what is left on the plate.
Good luck