How can I check who sent the message I accidentally deleted?

You can check it later on China Mobile's website.

Or go to the business hall to print your phone bill list this month (bring your ID card).

Generally, the billing system has a delay of several hours, which may be further delayed in case of holidays and peak crowds.

Only the number of the other party can be seen on it, and no information content is provided.

======================

Just take your certificate to the business hall and print the list of calls and text messages so far this month.