My future (and past) events added to my calender keeps on disappering, how can I stop this, please?

At first i thought perhaps your sync time block was off, but that shouldn’t affect future events.

Settings > Calendar > Sync >

Q1: Were these events created on the iOS native calendar, or through some other app or service (e.g. Google Calendar)?

Q2: Is your date & time set to automatic? (If someone would set a custom time, that would give weird results when syncing a calendar.)