Please check it the extension is still installed: Tools > Extension Manger.
If not install it again.
EDIT
A new installation is also what I would do/recommend. However, I would remove also the LibreOffice Application folder by renaming it.
After you installed LibO remove/rename the LibreOffice Application folder. In W7 the Application Folder should be somewhere under your user name. Go into it and you find a folder LibreOffice. Renaming it is enough
Now reboot your machine and start a new application.
I am not sure if W7 still used the Sytem Restore like XP. If so, before starting the new installation, you could possibly also make restore to a system point prior to the installation of the 4.2.8 version. I typically make a new restore point before I upgrade LibO on my XP machine.
After the installations check the spell checker. If all works fine you can replace folder by folder the new folder in /Application Data / Libre Office by the old ones which you save be renaming the folder containing all. By doing so you get all your customization back. However, you better test the spell checker after each replacement to see in which folder the problem was.
,
Before I install a new version of
LibreOffice I always copy the old
package and rename that as
LibreOfice4_old.
I don't understand what this package is. From where do you take this package, what is its content, and where do you save it?