In order to replace damaged roof shingles you need to remove the damaged shingle install the new one and seal the edges.
How to replace damaged shingles on a roof.
Slide the new shingle up into place and secure it with four nails.
Removing 3 tab shingles using a flat bar to do a repair.
In that case tear out the damaged shingle and cut v notches in the replacement to fit around the four nails.
Use the claw of a hammer to loosen the adhesive under the tabs 2 rows above the damaged shingles and then loosen any exposed nails with the claw.
We had a wind storm recently blow off one shingle and damage 3 shingles on our garage.
How to replace a damaged roof shingle without changing entire section of roof.
Carefully lift the upper shingle and secure the new shingle with roofing nails.
We had to replace them and all the roofing companies said to do it ourselves because its easy winds of 100km the yard was a mess garbage shingles toy pools.
Asphalt roof shingles can be easily damaged by high winds and falling tree limbs.
How to replace a damaged shingle.
In the photo below the target shingle perhaps it needs replacement due to damage from a falling object or roof pests is located.