You can press the button back if you drop it. First press the bracket back, but pay attention to the direction, positive and negative. Then align the key cap with the direction and press it down with a little force. The sound of "click" indicates that the key cap is stuck on the bracket. Use your hand to gently break it upwards and check whether the four corners are stuck. However, it should be noted here that if the keyboard keys fall off due to some falling and bumping, the support of the keys may have been damaged. Please check carefully before installation. If it is damaged but not serious, it can still be used. If the support has been broken, it needs to be replaced with a new support before it is installed and used.