To re-enable the bookmarks bar:

If you have the orange firefox button: Click on it and move your mouse over options (don't click). Then click on bookmarks toolbar. (Clicking on menu bar will take you back to the normal file/edit/view menu instead of the orange button, by the way)

If you have the normal file/edit/view/etc menu: got to View, and select toolbars. From there click on bookmarks toolbar (and any others you want to turn on)

If your bookmarks don't appear to be there after you get the bar back, then I have a question. Did you just install the new version, or did you uninstall the old one first? Did you install firefox to the same location on your computer?

In response to your question, the computer was updated at the suggestion of the program and to the best of my knowledge nothing was uninstalled. I use the program on several computers and fortunately didn't update all of them--the only one that was updated was a Windows 7 OS and it doesn't work--fortunately the others that weren't updated still work, but I need the other one to work as well

and, by the way, your fix didn't work

Firefox doesn't "lose" bookmarks during an update, and even if it did you should see the default bookmarks that come with Firefox. Plus, Firefox 4+ versions have ten bookmark backups stored in your Profile folder; Firefox 3.6 and earlier stored five backup files.

Were your bookmarks even being saved in Firefox, or maybe something like the Google Toolbar or a Yahoo Toolbar extension??
Those two extensions haven't been updated for Firefox 5.0 (to the best of my knowledge, unless they were updated in the last couple of days), so those extensions would have been disabled during the update due to the lack of "compatibility".

To see if that is the case, open the Add-ons Manager tab - {Ctrl + Shft + A} - then open Extensions and see which extensions may have been disabled, they would appear at the bottom of that list and would be greyed-out.

Please check to see what extensions might be disabled.