The visa was torn in half before departure. Does it still work?

Is it a sticker visa affixed to your passport or a separate visa printed on A4 paper? If it is a separate visa, it will be easy. Print a new copy, or put the shredded paper together and make a copy. If the sticker visa on the passport is torn off, it is estimated that the passport page is also damaged, which belongs to passport damage. Generally speaking, if your passport is damaged, you need to issue a new one. Passports and visas are badly damaged, so it's hard to say whether they can be used. If you are lucky, you may be able to pass the customs if you meet an accommodating border inspection or immigration official.