■To get back the option to start from previous tabs Try: Tools -> Options = General tab, startup

• click the button [Use Current Pages]

Hope it works.

■ You ask have i know lost ALL my work?

■ Note, it may make sense to store your 'work' as bookmarks or groups of bookmarks & or to store your 'History'

• restore files may exist and one backup of them, but they are not really intended to store work on. You may be able to recover them from your profile, but as you probably continued to use firefox whatever large one you had is probably long gone.

■ Now to try to get back whatever you have lost, this is relying on the fact that latest versions of firefox store for I think 5 days auto backups.

• immediately backup all your current history/bookmarks by exporting to another file somewhere maybe in your Vista desktop for now. see Backing up and restoring bookmarks. If you fail to do that you may accidentally overwrite whatever you do have. see Restore bookmarks from backup or move them to another computer
• one thing worth trying - it is clumsy & time consuming but relativity safe and easy - search your computer for all files ending .JSON there will probably only be a handful of them unless you already have backed up bookmarks deliberately, copy and save them you may find them usefull later on.
• do the manual backup of your bookmarks again as you work to restore whatever you have lost, using a different filename, each time so you have something that will not be lost. This is because it is all to easy to accidentally overwrite and therefore permanently loose bookmarks.
• to try to recover any auto backups that firefox made, remembering these will include whatever History was saved at that time have a look at its about AUTO backups

hi thanks for the reply. I do have my history but how would i access the restore page? you said "You may be able to recover them from your profile" how do i access my profile?

Session restore works more reliable if you choose Tools > Options > General > Startup: "When Firefox Starts": "Show my windows and tabs from last time" instead of relying on the Save & Quit dialog.

Firefox stores session data in the file sessionstore.js in the Firefox Profile Folder

Help > Troubleshooting Information > Profile Directory: Open Containing Folder

See also http://kb.mozillazine.org/Session_Restore

great! found them in the profile how do i open them?

nobody kno how to open them no?

As explained by cor-el from the link provided

If neither your old session nor the Restore Session error page appears after a crash, or you accidentally click on “Start New Session”, you can enter about:sessionrestore in the Location Bar (address bar) to force the Restore Session page to appear, after first restoring a backup file to restore the old session data. The session data is stored in sessionstore.js; this file can be restored (while Firefox is not running) from backups, including "sessionstore.bak". The file "sessionstore.bak" is created if you launch Firefox after a crash has occurred. It is a copy of the current sessionstore.js that gets lost otherwise, if you restart Firefox. [4]

Note

• .js files will actually open in firefox, or for that matter some text editer, if you want to view the content. You should be able to recognise the individual links , copy and paste them is them to another document and open them that way.
• if it is a long complex list and you want them to open as a proper restore session follow the instructions as above (read the original text it includes links that I have not copied correctly)