There are several reasons why you might be experiencing this problem. This could be caused by an individual attempting to gain access to an IT account. However, it could be that the cached login details on a PC or mobile device are incorrect. After a password has been changed, the device may attempt to login with incorrect credentials. After several attempts the account may become locked.
You should ensure that you check all computers and devices that you might have used recently. You should check whether any applications have an out-of-date password stored.
If the problem persists and you are sure that you have amended your credentials on all possible devices, report an issue with your University IT account.