Litecoin wallet won't decrypt

My Litecoin Core wallet won’t accept the passphrase I set up. I’m reasonably sure I am using the correct passphrase. Can the wallet become corrupt on Windows 10? I tried the back up that I saved offline and it also won’t decrypt. Anyway to recover the coins? Coinbase won’t send the private keys. I’ve tried different software to guess/hack the passphrase but have had no success. I couldn’t get Hashcat to work and looks like some other software is necessary to get files set up for it to work.

did you upgrade or change the wallet software resently?

no that I know.

what do you mean with this? why should coinbase send you a private key, mind explaining why you think they should do such thing?