Some tricks I’ve used in the past when hugge sets of episodes are scrambled or misnamed and you need to start from square one matching them:

• Check if there is any embedded metadata with the episode name or number with a tool like MediaInfo
• If the episodes have different runtimes, you can try to match them to runtime listed on a well-labeled list of episodes, like on Wikipedia or in a torrent.
• Download a tool to auto-generate subtitles from the audio track. Probably won’t be accurate, but should give you enough of the dialog to now search online and see what episode it is.
• If the show has a splash screen with the episode name at a fixed time, like many kids shows, you can auto-generate thumbnails at that time for all episodes
• Last resort: Manually watch enough of each episode to match it to the right episode synopsis on e.g. wikipedia and then label it appropriately
• Pirate option: Pretend you ripped it yourself and download a properly-curated set