Hello members and guest
If the bezel does not turn or hard to turn, what I did is spray some WD40. It will work. But cautious check if your watch is still water resistant.
My experience is that WD40 must be used sparingly and with extreme care. At one time, I was convinced WD40 was god sent when it came to stiff bezels. Until I sprayed some onto one vintage seiko 6306 diver and later found that the low viscosity WD40 liquid had seeped into the case and heavily stained the entire movement. Both the rubber gasket under the bezel and under the caseback had turned mouldy and sticky.
When it comes to sticky bezel, I prefer to remove the bezel, clean the dirt under the bezel with a toothbrush. Spray some WD40 onto a soft cloth and wipe the part of the case with which the bezel comes into contact. I prefer not to spray directly onto the watch (unless the movement has been removed from the case).
Another experience is that WD40 may discolour the bezel insert of vintage pieces because it contains petroleum distilates. So, think twice before you spray..

Hope the above are of some help.