Any suggestion would be appreciated
Two things: 1) make a full backup now so that if anything else happens you can at least get back to this point.
2) If you haven't already done so: contact your host, speak with them very calmly, and ask them nicely if they can restore the files from the backup before you did the upgrade. You want the whole
wp-content/themes directory restored. They may charge you for that.
Without a link it's just a guess but it sounds like you modified the Twenty Ten theme in the
When you updated you lost your modifications and that's the number one reason to create a child theme.
If you can get the old
wp-content/themes/twentyten directory back, leave the current one alone and put the old one in
style.css file in that new
twenyten-jaimeh directory and change the name from
Theme Name: Twenty Ten
Theme Name: Twenty Ten Jaimeh
Then activate that theme and hopefully it will all work.
If Something Really Bad™ happens then restore your own backup from step 1. That will put you back to the way you are now.