I've had a look. The pages that show, seem OK to me. That doesn't say anything about any changes you may have made...
Start by pressing <Ctrl-F5>
If that doesn't work:
Clear your browser cache.
If that doesn't do it...
Start by making a back-up of the current situation, so you have a fallback position should trying to fix things not work out. [see bottom of this text]
Next: de-activate the gallery plug-in, but keep the data!
FTP: Install a fresh copy of the gallery
Check the result
== == ==
How to make a back-up of your site
- FTP: Make a backup of the files of your site, using FTP 'Filezilla' [free] or your own FTP-program.
(see: http://codex.wordpress.org/Using_FileZilla )
- Make a backup of the CONTENT of the site
- dashboard > tools > export > all content > download exportfile
- If required: confirm installation of export tool and run the export
You now have a fallback position, should things go wrong!
NOTE!!! Make these backups every time BEFORE you make changes!
Repairing problems becomes much easier!!
For future reference:
Restoring a backup goes 'the other way around:
Make sure you have the most recent OK version of a backup.
- Restoring files: FTP one / more / all files from the backup to the site, overwriting the files on the site.
- check the results! If all problems are solved... Done!
- has some content vanished...? Or do you need to go a 'step back'?
- Dashboard > Tools > Import > wordpress > choose the exportfile from your computer, and 'upload file and import
NOTE!! The database = CONTENT goes BACK to the previous state. Changes
made since the backup was made, you will have to re-enter. So regular backups - daily / weekly - are advised!!