Student or Learner
Can you please tell me the sentence below is correct ?
I lost my phone yesterday in the event. If anyone found it please contact me.
It also depends on everyone knowing which event you mean- it might be better to name the event. In a busy city with many events every day, it might not work.
I would use either "If anyone finds it, ..." or "If anyone has found it, ..."
If you are emailing the people in charge of lost property at the event in question, it's OK to use "at the event".
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.