Language on both my blogs got corrupted – please help

I have two blogs – https://www.elifsavas.com/blog and https://www.elifsavas.com/yazilar. Both are in Turkish. I did nothing to them – no upgrades, no database changes, nothing – and when I woke up this morning, I find that I and my readers are seeing weird characters instead of Latin (English) and Turkish letters. (Characters like EL?°F Sava?? Felsen – H??th??t Ku??u) I searched the forums and tried to rem out two of the lines in wp-config.php, but nothing works – please help. It’s also happening in both blogs, which are separate installations! Many thanks.