No. Did you first check under the sounds settings to make sure you still have sounds selected for the incoming rings? After that did you try a soft reset to fix the problem? If yes to both, then I'd try a hard reset and if it still doesn't ring it would have to be bad hardware.
Main Phone: Treo 270/600/650/700w/700p/750v/Motorola Q/iPhone
Tried but sold: Motorola Q/Nokia E61/700wx/HTC TyTN/Treo 680
I figured it out in the end. What had happened was where i had previously installed SPB Pocket + and lost the use of the volume buttons on the side, they had turned the phone volume down to mute, so i could hear text messages, as they are included in the PDA volume. By installing the fix from SPB i was able to gain control of the volume and turn it up again therefore restoring the ringing.
Nokia 3210 > Nokia 3310 >Palm Vx > Palm M105 >Treo 180g and Nokia 8850 > Treo 270 > Treo 600 > Sony TH55 > Tapwave Zodiac 2 > Treo 650 GSM > Imate KJam > Treo 750v