i bought an second hand iPhone 13 but its locked to the previous owner and he doesnt respond

Take it back to the person from whom you received it. Get them to do the things in this support article or ask for a refund --> What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support

Unless you have the account information that set the lock, or the original receipt from Apple, you cannot remove the lock; recycle the device. Read this article about how to remove Activation Lock --> How to remove Activation Lock - Apple Support

If you are not the owner and do not have the Apple ID and Password then there is no way that you can get into this iPhone unless the original owner shares the Apple ID and password with you. If you are lucky you can get into this iPhone if they (owner) accidentally remove the device from their Apple ID.

Contact the person ad ask them to do the steps in the articles. If they will not, ask for a refund. Unless they also sent you the receipt from when the item was purchased from Apple, the iPhone cannot be made usable by you without that account information.

Realize that it is not uncommon for thieves to sell used iPhones with this lock feature on it. Unfortunately purchasers are not always aware of this feature and in the end they have no option but to recycle the device and regard it as a learning experience.