Hey @Dragonrana 
Did the tips provided by @Original_Lucy help you access your voicemail?
If you're still having trouble, please don't hesitate to contact customer service so they can look into it with you!
Hi @Dragonrana sorry to hear that you are having difficulty accessing your voice mail. Did you restart your device to clear the cache and memory. Sometimes that will correct your access number. I don't know where you are but you can check the access number Here . Scroll down and see if you have the right access number or perhaps it was deleted by some chance
