Thanks & regards,
If the server throws the ball into the air to make a serve, but misses the ball completely, it is a point for the receiver.
Law 2.6.3 of the Laws of Table Tennis states:
As the ball is falling the server shall strike it so that it touches first his court and then, after passing over or around the net assembly, touches directly the receiver's court; in doubles, the ball shall touch successively the right half court of server and receiver.
In addition, Law 126.96.36.199 states:
Whenever there is a clear failure to comply with the requirements for a good service, no warning shall be given and the receiver shall score a point.
So in the case where the server throws the ball into the air to start the service, but misses the ball, the server has failed to comply with the requirements of a good service, and so he loses the point.