My girlfriend's birthday is the day after tomorrow. Because she was in a bad mood, she ignored her for several days, and she ignored me. I don't know what to do.

If you want to be together, don't have a cold war. It is very wrong to ignore it when you are in a bad mood.

Why don't you show up with a surprise on her birthday and tell her that you snubbed her on purpose, just to surprise her birthday. No matter how much she blames you, stick to this point and say something nice, you will make up, but don't ignore people easily in the future. You'd better give her what she wants most when you are together. Flowers are essential. Find a romantic restaurant to eat. Romantic atmosphere will make girls feel very happy and help you make up.