Can't hear anything in "normal" mode, only in loudspeaker mode.

You need to isolate the problem. Try connecting a headset first, if you hear music coming out of the headset, then there's a problem the speaker and needs to be repaired.

But if there's no sound coming out of the headset either, then you need to check the phone or sound settings of the phone. You may simply navigate it or refer to the user manual.

If you get the same problem after modifying the settings, then bring it to the Nokia Care Center for repair.

Hope this helps and have a great day!