Yes, you can. A deleted personal voicemail is not displayed in a user's inbox but the voicemail is still retained for 14 days before it is permanently deleted. Our user interface does not yet provide a mechanism to display deleted voicemails and to undelete them. In the meantime, I suggest contacting our customer support so they can undelete a voicemail for you.
If you are a developer using our APIs directly you can undelete a voicemail programmatically. Please refer to https://developer.mypurecloud.com/api/rest/v2/voicemail/index.html#patchVoicemailMessagesMessageId