iTunes Error Message 54
Step one - https://support.apple.com/en-us/HT205597 - following all the links - especially on a PC might take two hours or more depending on how good you are with troubleshooting security on PC OS.
Step two - get more logs/detail - take notes of the articles above in case you didn't do what they asked and instead did what you thought was correct 
Step three - ask a follow on question or contact Apple support with the "more logs"