No matter how it happened, a damaged side view mirror should be replaced as soon as possible. As frustrating as it is to take time out to have it repaired, a damaged side mirror is both a visual and safety hazard. You can take a trip to the salvage yard for a new mirror or order one online or through your dealership if you know how to replace a car side mirror, instead of traipsing to the workshop.
If it’s only the mirror section of the side view mirror that has been broken, then you only need to obtain replacement glass from the auto parts shop. The question of how to replace a car side mirror then becomes so much easier to resolve as well. There may be a waiting period for the glass to arrive, and that time can be used to gather the supplies you will need to attach the new piece of glass to its frame. This is also the time to remove the broken pieces of mirror from the frame. You should protect yourself from getting cut by the shards with heavy-duty gloves. Any dried putty should also be removed.