Calendars not syncing

Welcome to the Apple Community.

1. First check that all your settings are correct, that calendar syncing is checked on all devices (system preferences > iCloud on a mac and settings > iCloud on a iPhone, iPad or iPod).
2. Make sure the calendars you are using are in your 'iCloud' account and not an 'On My Mac', 'On My Phone' or other non iCloud account (you can do this by clicking/tapping the calendar button in the top left corner of the application ), non iCloud calendars will not sync.
3. If you are sure that everything is set up correctly and your calendars are in the iCloud account, you might try unchecking calendar syncing in the iCloud settings, restarting your device and then re-enabling calendar syncing settings.

I have tried all the steps you suggest, but still nothing !

I'm not saying you haven't, but one of those methods seems to resolve the vast majority of syncing issues, usually it's number 2. Are you sure you checked for non-iCloud calendars properly.

Yes I have double checked. One curiosity though is that on both iPad and iPhone when checking the account settings, the length of the password was wrong. I re entered the correct password (on both), clicked done, and everything was ticked. Then went back into the account info and the password was once again the wrong length, again on both devices!

If you are talking about the number of dots, I wouldn't worry about that, part of the security of a password is not knowing how long it is.

Thank you for helping me with this. Should I make a difference if my PC is away for repair?