All calendar events suddenly deleted on iPhone

Hello! Starting from yesterday, all my events from calendar was gone. I didn’t do anything, I keep all my events there and when I entered to check something, everything was deleted. I didn’t had backup because of lacking space on iCloud so i thought that’s the problem, I payed iCloud plus, i updated to the last iOS, I tried to restore it online, but nothing changed. I checked the sync, the account, everything. I don’t know what to do and I need everything come back to normal! Please help! Thanks!

[Re-Titled by Moderator]

Original Title: Deleted events from calendar