First, verify that the problem is not affected by ipad and phone settings. shut down ipad and phone and send message to yourself. see if it comes in to PC. if it does, that would indicate that one of the other devices is retrieving and deleting (POP account). Since those devices are often used more than the PC, the messages may be gone by the time PC checks.

If that is not the issue, then we need to see screenshots of error messages and screenshot of incoming server settings for PC. thank you.