“不知打哪儿来”可以翻译为 “I don't know where it/he/she/they (depending on the context) came from” 。
如果具体语境中指的是某个事物，比如“不知这股风打哪儿来”，可译为 “I don't know where this wind came from” ；若指人，像“不知这个人打哪儿来”，可译为 “I don't know where this person came from” 。