language dutch installed

[lat9]

I have read it again "DrByte's instructions in the link that mc12345678 posted" can I do those sql instructions on the present database or on a back-up from a few days ago ?

I'd start by making a backup of your current database (even though it's currently "got issues"), just to be sure. Then, remove the Dutch language from your store and make sure that your default language (per DrByte's post) is still enabled. Next, I'd copy the SQL queries that DrByte provided in his posting, paste them into Tools->Install SQL Patches and run those queries. Finally, I'd head to Catalog->Categories/Products to see if the issue's been corrected.

Hopefully, that will correct the issue, but YMMV.