Crashing is part of flying. Repairing isn't any different from building. Just pick up all the pieces and puzzle it back together. Or cut new parts to replace the badly damaged ones.
Most of my crashes are straight forward, poor judgement, user error, or simply a poor flying plane pushed past its limits. I can think of two hardware failures, one was a 3-line Brodak bellcrank that came apart, the other was a nylon horn that let go after 10 years of service and a rough life.
Many of my planes have been crashed. I've also spent a lot of time in the last year or two rebuilding, restoring, overhauling older planes. Usually a repair or rebuild is very quick and sometimes the repair isn't even noticable on the finished product. As long as the wing is intact I usually can salvage it. I have been known to reuse Skyray 35 fuselages though.