Can anyone please help me about this that why an electron has a spin motion and what will happen if it stops spinning.

We believe that electrons have a spin moment because empirical measurements indicate that the electron has an intrinsic angular momentum and an intrinsic magnetic field. What is not known is the precise cause of these intrinsic properties. Magnetism of a substance seems to be the result of alignment of the angular moments of the electrons that are unmatched by electrons with an opposite "spin".

 

One popular explanation is that the electron's mass and spin have an electromagnetic origin. If the spin has electromagnetism as its origin, then we could say that spin is a result of the angular momentum of the electromagnetic field. Furthermore the electron would be the smallest magnet.

 

if the electron is an electromagnetic field with an angular moment (as opposed to a photon which seems to be a traveling electromagnetic field) and has apparent mass due perhaps to its standing nature, if the angular moment stops, it would cease to be an electron.

Spin (as used in this context) is an intrinsic angular momentum and not a physical spinning of the particle. An electron cannot cease to have spin, as it is an intrinsic property.