If you no longer see that History in the sidebar (View > Sidebar > History) on the the Library (History > Show All History) then that history is gone.

You didn't post your Help > Troubleshooting Information information, so I can't check your history settings.

You can look at these prefs on the about:config page.

• http://kb.mozillazine.org/browser.history_expire_days (180) (also affects saved form data)
• http://kb.mozillazine.org/browser.history_expire_days_min (90)

To open the about:config page, type about:config in the location (address) bar and press the "Enter" key, just like you type the url of a website to open a website.
If you see a warning then you can confirm that you want to access that page.

Thanks for replying, but i still can't figure out how to go back to the 29th aug to see browsing history. it only ever shows today and yesterday. Heather x

Did you check the above mentioned prefs on the about:config page to make sure that you keep history for more than 7 days?

See also http://kb.mozillazine.org/about%3Aconfig

Yes I have done this, but it was the last 7-8 days I wanted specifically- Sat 29th Aug. But I think it's all gone forever sadly!!! I dont think there is any way to get it back as it is still saying only the last 2 days!!! Ive even restored to an earlier date and it still won't show anymore than 2 days, even when I havent deleted it. This is just Firefox if I had gone through internet explorer I would of found what I was looking for. Thanks for the help and advice - Heather x