You were not notified because it was unscheduled. This, unfortunately, is not uncommon.
The nature of a FREE instance is that it does not have any support and the availability is not guaranteed. There is nobody to contact for help. My suggestion is to adjust your expectations and how you approach it. Any work that you want to keep should be, to the extent possible, contained within a scoped app that is linked to a git repo and back it up frequently. For any data or global work that you want to keep, I suggest working with update sets and record export XML files. Export those so you can save them to the git repo separately.
If the message does not go away after a week or so, it's possible/likely that something with your PDI has been corrupted and you will need to release it and request a new PDI. You can wait as long as you like or until you decide the wait is too long... it's up to you how long you wait... it may come back or it may not.
Most of us have lost at least some work over the years so you're not alone!
Good luck!
