I can't generate certificates in Fiddler anymore, and I think I've broken it somehow

I was recently going through and deleting all of the Fiddler certificates on my PC, and I swear I thought I only deleted the ones with "DO_NOT_TRUST" in the name.

However, now whenever I try to enabled HTTPS decrypting I get various errors at various stages, including:

19:37:46:5079 !ERROR: Failed to generate Certificate using CertEnroll. System.Reflection.TargetInvocationException Exception has been thrown by the target of an invocation. < CertEnroll::CX509Enrollment::_CreateRequest: Keyset does not exist 0x80090016 (-2146893802 NTE_BAD_KEYSET)

19:40:01:3153 !Fiddler.CertMaker> The Root certificate could not be found.

19:40:29:8745 DefaultCertMaker: GetRootCertificate() did not find the root in the Windows TrustStore.

I've tried everything possible to fix this. I've restarted my PC, I've reinstalled Fiddler, I've cleared the keys from AppData/Microsoft/Crypto etc. Nothing works. I don't know what to do. I need this to work.