@Oregonerd go to Menu -> Settings -> Home and Startup
Make sure "Open previous windows and tabs" is ticked in the Startup section
If that's not working, usually one of two reasons:
• you're using a private window (it'll say "private browsing" in the top right), where this isn't possible
• you've set Firefox to clear certain data when you close it
For the latter, go to Menu -> Settings -> Privacy and Security, then check the following:
1. "Clear cookies and site data every time you close Firefox" is not ticked
2. "Remember history" or "Customise history" is chosen in the History section
Then if you use "Customise history", click "Choose what you want Firefox to remember" and check:
3. "Always use private browsing mode" is not ticked
4. If "Clear history when Firefox closes" is ticked, click Settings below that and check what you're asking to be cleared each time you close Firefox. It won't be able to restore sites if you're asking for "browsing and download history" to be cleared, and "cookies and site data" probably needs to not be cleared also
