...started installing things again and recovering things from my backup, which will take a while. But what else could I expect when upgrading straight from Squeeze to Jessie? Yes, I took way too long to upgrade, there was always something more urgent to do.

Anyway, I've just reinstalled Firefox on top of the Firefox folder I had restored from my backup and it worked wonderfully! It kept all my cookies and even remembered which pages I had open before I reformatted the hard drive! XD

Anyway, apologies to anyone here who's not a computer nerd (although if you're not one and you've read this far, I must congratulate you). I just felt I needed to share.

Now after I'm done restoring my home directory from my backup, I will go to bed and continue restoring things tomorrow.

Also, cp -a is a good way to make backups. I.E. it worked.