What a headache!
After my website was hacked by some add site, I finally managed to get it back online. It wouldn’t have been possible without the kind help of mr. Broco, main developer of y!Gallery. We managed to recover the original pages from some backup, and after some tweaking, it’s working again. Anyway, I hope this doesn’t happen again, and I’ll be sure to keep doing backups more often!
Sorry for the wait and again, thanks for your patience!