Help recover my calendar entries please

Last night I clicked synch Calendar with iCloud and woke up this morning to notice that all my calendar entries had vanished!

I have read through some helpful tips like ensuring ‘ALL entries’ are chosen in the calender settings but my iPhone setting was already on all entries when I checked my settings.

Please can someone help me? It’s urgent all my work orders are scheduled here and I have no backup whatsoever. Afraid to miss a clients order