Hi Linda ...
Now I get a back screen with funny writing, then a message in several languages to restart the computer. I've done this several times
Otherwise known as a kernel panic.
A Safe Mode boot takes much longer than a normal boot so be patient. Once you see the Desktop, click the Apple menu icon top left in the screen. From the drop down menu click Restart.
Disconnect any peripherals before booting in Safe Mode.
Well after that suspenseful few days I think we are back on track. So from what I am getting, it is the update to Thunderbolt that caused the kernal panic error. By running recovery mode most people, including myself were able to get back to normal. I did read that someone was having problems with the recovered OS recognizing the drives or partitions involved. I'm not sure what would cause that, but if I were to try anything it would be to try and do recovery again. Make sure the destination for the recovery is correct. I also went back about a day and selected the backup from there. Today I successfully updated all software, I still did not notice an update for Thunderbolt in the selected items. Everything seems to be working well now. Thanks to the community for providing the timely information needed to resolve, correct, and understand this issue. I do think Apple needs some better assistance procedures and protocols. I don't think asking a question should be charged from the beginning, that just seems in bad form. Especially something that is Apple's fault.