Is my visa still valid?

Whether the visa is valid depends on whether your visa is within the validity period.

Visa is the annotation or label of a country's sovereign authority on passports or other travel documents held by its own or foreign citizens. Stamps or labels have a clear explanation, indicating that they are allowed to enter or leave the country or go through the procedures in the country. It can also be said that it is an endorsement certificate issued to them. Visa is an act of national sovereignty, and it is a concrete embodiment of a country's control and management over the entry of citizens from other countries, so as to achieve the purpose of safeguarding national security and domestic social order.