Is there a service to review prior flight plans?
Lockheed Martin Flight Services (LMFS) provides a history of filed flight plans on their web site under Flight Planning &amp; Briefing | History. The path to the particular page is: https://www.1800wxbrief.com/Website/showPilotHistory. 

Unfortunately, only the last 15 days are available. So if your flight plan is older, it won't be displayed. Additionally, if you're filing your flight plans through a service provider that doesn't provide full LMFS integration (e.g., ForeFlight) it won't be displayed even if within 15 days. In this case, you'll need to refer to your service provider's interface.