If you find that you have lost your bicycle key, first think about whether you left it somewhere to look for it, or whether you have a spare key at home and go home to get it. If you don't have a spare key at home, you can contact a professional mechanic to solve this problem.
Of course, you can also try to pry the lock cylinder violently with a screwdriver. You don't have to open the lock to destroy the lock core. Or use pliers to stabilize the lock head, and then beat the lock head with a hammer to try to shake out the lock cylinder marble. You can also use local materials and find a big stone to break the lock.
If you know where to unlock the lock, you can ask a friend for help and take the bike to the garage for repair. If the environment is at night, you can also choose to call the police to solve the problem.