I left something on the train.
'Dimenticato' — di-men-ti-CA-to. Stress on the fourth syllable; five syllables total.
Say this immediately to a station attendant after realising you have left belongings on board. The faster you report it, the better the chance of recovery.
'Ho dimenticato' is the passato prossimo of 'dimenticare' (to forget/leave behind). 'Qualcosa' is an indefinite pronoun meaning something — it is invariable (does not change for gender or number). 'Sul treno' means on the train (su + il).
Ho lasciato la borsa in carrozza.
I left my bag in the carriage.
'Lasciare' is more neutral — you left it, not necessarily forgot it.
C'è qualcuno che ha trovato un ombrello?
Has anyone found an umbrella?
Use on the platform hoping someone picked it up.
Posso parlare con un responsabile?
Can I speak with a supervisor?
Escalate when the attendant cannot help.
Lost items on Italian public transport are collected by drivers or cleaners and brought to the depot at the end of the line. They are then transferred to the city's lost and found office. Recovery rates for valuable items are low but umbrellas and bags are often returned.