LightMap Crash, can't build

Hey, i deleted a file from my HDD a now i can’t build and i don’t have the red message in the right side of my screen. I installed again the engine and the launcher but the problem is again and again here. I don’t know what i can do, i send you the error :

<None> === Lightmass crashed: === Assertion failed: DLLHandle != nullptr [File:D:\Build++UE4\Sync\Engine\Source\Runtime\Core\Private\Internationalization\ICUInternationalization.cpp] [Line: 257] 0x00007ffdf2a1a388 KERNELBASE.dll!UnknownFunction ] 0x00007ffd8acf4a10 UnrealLightmass-ApplicationCore.dll!UnknownFunction ] 0x00007ffd8250955c UnrealLightmass-Core.dll!UnknownFunction ] 0x00007ffd8249aa4d UnrealLightmass-Core.dll!UnknownFunction ] 0x00007ffd823f147b UnrealLightmass-Core.dll!UnknownFunction ] 0x00007ffd823e82f7 UnrealLightmass-Core.dll!UnknownFunction ] 0x00007ffd823d724c UnrealLightmass-Core.dll!UnknownFunction ] 0x00007ffd826cbc6f UnrealLightmass-Core.dll!UnknownFunction ] 0x00007ffd824a6641 UnrealLightmass-Core.dll!UnknownFunction ] 0x00007ffd824bf4d6 UnrealLightmass-Core.dll!UnknownFunction ] 0x00007ffd8244b36a UnrealLightmass-Core.dll!UnknownFunction ] 0x00007ff6640177ba UnrealLightmass.exe!FMatrix::InverseFast() ] 0x00007ff6640809c8 UnrealLightmass.exe!Lightmass::FStaticMeshStaticLightingMesh::Import() ] 0x00007ff663fdb1a5 UnrealLightmass.exe!Lightmass::FLightmassImporter::ImportObjectArray<Lightmass::FStaticMeshStaticLightingMesh,TMap<FGuid,Lightmass::FStaticMeshStaticLightingMesh * ptr64,FDefaultSetAllocator,TDefaultMapHashableKeyFuncs<FGuid,Lightmass::FStaticMeshStaticLightingMesh * ptr64,0> > >() ] 0x00007ff66400f4c3 UnrealLightmass.exe!Lightmass::FScene::Import() ] 0x00007ff663fef709 UnrealLightmass.exe!Lightmass::BuildStaticLighting() ] 0x00007ff66401a922 UnrealLightmass.exe!Lightmass::LightmassMain() ] 0x00007ff66403d49a UnrealLightmass.exe!main() ] 0x00007ff6640c0bdc UnrealLightmass.exe!__scrt_common_main_seh() ] 0x00007ffdf4ed3034 KERNEL32.DLL!UnknownFunction ] 0x00007ffdf5841431 ntdll.dll!UnknownFunction ]