Whenever any program crashes (not just unreal), there is always a high possibility that the work done will be affected due to memory load failure. I’m afraid, you will have to redo again, create a new class and copy-paste the whole thing again if your fix attempts meet a dead end.
Also, is there a reason why you think your engine crashes? This is something that supposedly does not occur regularly. If it does, then you might have missed some required steps to use the engine. First thing first, does your computer meet the minimum requirements to run Unreal? Are there any outdated/experimental plugins that you think affect this? Does your GPU support DX12?