System restore failed to extract file with Windows Defender .dll error

I have used System Restore regularly through the years without any issue until this week. I tried System Restore from a variety of restore points over the past three months. Each attempt ended with a restart and this message:


System Restore failed to extract the file (C:\Program Files\Windows
Defender\en-US\MpAsDesc.dll.mui from the restore point. The restore point was
damaged or deleted during the restore.


System File Checker found but did not fix .dll errors for Windows Defender:


MpEvMsg.dll.mui
MsMpRes.dll.mui
MpAsDesc.dll.mui
MpEvMsg.dll.mui

" of Security-Malware-Windows-Defender.Resources, Version = 6.1.7600.16385,
pA = PROCESSOR_ARCHITECTURE_AMD64 (9), Culture = [l:10{5}]"en-US", VersionScope
= 1 nonSxS, PublicKeyToken = {l:8 b:31bf3856ad364e35}, Type neutral, TypeName
neutral, PublicKey neutral in the store, file is missing
2014-07-07 01:57:34,
Info CSI 000003b6 [SR] Cannot repair member file
[l:30{15}]





There are 12 files under C/Program Files/Windows Defender, last modified in 2013 or earlier. Four of those same file names but with slightly different sizes are also under C/Program Files (x86)/Windows Defender. I tried to manually start Windows Defender in the services.msc menu without success and this error: <Failed to read description. Error code: 15100>


Would reinstalling a clean new copy of Windows Defender fix the .dll errors and also the System Restore errors? Is there another way to activate Windows Defender? Should the Windows Defender files be combined in the same Program Files or fully set up in both Program Files listings?